diff --git a/backend/character/test_data_helper.go b/backend/character/test_data_helper.go
index 1cceb6a..e63666a 100644
--- a/backend/character/test_data_helper.go
+++ b/backend/character/test_data_helper.go
@@ -41,7 +41,7 @@ func createTestSkillData() error {
 
 	// GSM Test-Skill erstellen
 	gsmSkill := models.Skill{
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Name:         "Menschenkenntnis",
 		Beschreibung: "Test Skill",
 		Quelle:       "Test",
@@ -56,7 +56,7 @@ func createTestSkillData() error {
 
 	// GSM Test-Spell erstellen
 	gsmSpell := models.Spell{
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Name:         "Macht über das Selbst",
 		Beschreibung: "Test Spell",
 		Quelle:       "Test",
diff --git a/backend/gsmaster/export_import_test.go b/backend/gsmaster/export_import_test.go
index adcc8ab..f24aca5 100644
--- a/backend/gsmaster/export_import_test.go
+++ b/backend/gsmaster/export_import_test.go
@@ -19,7 +19,7 @@ func TestExportSkills(t *testing.T) {
 	source := getOrCreateSource("KOD", "Kodex")
 	skill := models.Skill{
 		Name:             "Schwimmen",
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Beschreibung:     "Schwimmen im Wasser",
 		Initialwert:      12,
 		BasisWert:        0,
@@ -58,7 +58,7 @@ func TestImportSkills(t *testing.T) {
 	tmpDir := t.TempDir()
 	skill := models.Skill{
 		Name:             "TestImportSkill",
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Beschreibung:     "Klettern an Wänden",
 		Initialwert:      10,
 		BasisWert:        0,
@@ -114,7 +114,7 @@ func TestImportSkillsUpdate(t *testing.T) {
 	// Create existing skill
 	skill := models.Skill{
 		Name:         "Reiten",
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Beschreibung: "Alte Beschreibung",
 		Initialwert:  8,
 		SourceID:     source.ID,
@@ -349,7 +349,7 @@ func TestExportImportSkillDifficulties(t *testing.T) {
 
 	// Verify the difficulty was recreated
 	var imported models.SkillDifficulty
-	result := database.DB.Where("name = ? AND game_system = ?", "TestDifficulty", "midgard").First(&imported)
+	result := database.DB.Where("name = ? AND game_system_id = ?", "TestDifficulty", 1).First(&imported)
 	if result.Error != nil {
 		t.Fatalf("Difficulty not found after import: %v", result.Error)
 	}
@@ -364,7 +364,7 @@ func TestExportImportSpells(t *testing.T) {
 	source := getOrCreateSource("TEST_SP", "Test Spell Source")
 	spell := models.Spell{
 		Name:             "TestSpell",
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Beschreibung:     "Test description",
 		SourceID:         source.ID,
 		PageNumber:       42,
@@ -443,10 +443,10 @@ func TestExportImportAll(t *testing.T) {
 	database.DB.Create(&difficulty)
 
 	skill := models.Skill{
-		Name:        "AllSkill",
-		GameSystem:  "midgard",
-		SourceID:    source.ID,
-		Initialwert: 10,
+		Name:         "AllSkill",
+		GameSystemId: 1,
+		SourceID:     source.ID,
+		Initialwert:  10,
 	}
 	if err := skill.Create(); err != nil {
 		t.Fatalf("failed to create skill: %v", err)
@@ -562,7 +562,7 @@ func TestExportImportWeaponSkills(t *testing.T) {
 	weaponSkill := models.WeaponSkill{
 		Skill: models.Skill{
 			Name:             "Langschwert",
-			GameSystem:       "midgard",
+			GameSystemId:     1,
 			Beschreibung:     "Langschwert Waffenfertigkeiten",
 			SourceID:         source.ID,
 			PageNumber:       50,
@@ -616,7 +616,7 @@ func TestExportImportEquipment(t *testing.T) {
 	source := getOrCreateSource("TEST_EQ", "Test Equipment Source")
 	equipment := models.Equipment{
 		Name:         "Seil",
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Beschreibung: "10m langes Hanfseil",
 		SourceID:     source.ID,
 		PageNumber:   75,
@@ -663,7 +663,7 @@ func TestExportImportWeapons(t *testing.T) {
 	weapon := models.Weapon{
 		Equipment: models.Equipment{
 			Name:         "Kurzschwert",
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Beschreibung: "Einhändiges Kurzschwert",
 			SourceID:     source.ID,
 			PageNumber:   80,
@@ -716,7 +716,7 @@ func TestExportImportContainers(t *testing.T) {
 	container := models.Container{
 		Equipment: models.Equipment{
 			Name:         "Rucksack",
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Beschreibung: "Großer Lederrucksack",
 			SourceID:     source.ID,
 			PageNumber:   85,
@@ -767,7 +767,7 @@ func TestExportImportTransportation(t *testing.T) {
 		Container: models.Container{
 			Equipment: models.Equipment{
 				Name:         "Pferdewagen",
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 				Beschreibung: "Zweirädriger Wagen",
 				SourceID:     source.ID,
 				PageNumber:   90,
@@ -817,7 +817,7 @@ func TestExportImportBelieves(t *testing.T) {
 	source := getOrCreateSource("TEST_BL", "Test Believe Source")
 	believe := models.Believe{
 		Name:         "Kirche des Lichts",
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Beschreibung: "Hauptreligion in Valian",
 		SourceID:     source.ID,
 		PageNumber:   95,
@@ -1257,10 +1257,10 @@ func TestExportImportClassTypicalSkills(t *testing.T) {
 	database.DB.Create(&class)
 
 	skill := models.Skill{
-		Name:        "Test-Spurenlesen",
-		GameSystem:  "midgard",
-		Improvable:  true,
-		InnateSkill: false,
+		Name:         "Test-Spurenlesen",
+		GameSystemId: 1,
+		Improvable:   true,
+		InnateSkill:  false,
 	}
 	if err := skill.Create(); err != nil {
 		t.Fatalf("failed to create skill: %v", err)
diff --git a/backend/gsmaster/gsm_model_test.go b/backend/gsmaster/gsm_model_test.go
index 7733ce7..b1c4b7d 100644
--- a/backend/gsmaster/gsm_model_test.go
+++ b/backend/gsmaster/gsm_model_test.go
@@ -6,10 +6,19 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
+func defaultGameSystem(t *testing.T) *models.GameSystem {
+	gs := models.GetGameSystem(0, "midgard")
+	require.NotNil(t, gs)
+	require.NotZero(t, gs.ID)
+	return gs
+}
+
 func TestSkill_Create(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	testDefinition := []struct {
 		name    string
 		skill   *models.Skill
@@ -44,7 +53,7 @@ func TestSkill_Create(t *testing.T) {
 				return
 			}
 			assert.NoError(t, err)
-			assert.Equal(t, "midgard", tt.skill.GameSystem)
+			assert.Equal(t, gs.ID, tt.skill.GameSystemId)
 			assert.NotZero(t, tt.skill.GameSystemId)
 			assert.NotZero(t, tt.skill.ID)
 		})
@@ -54,6 +63,7 @@ func TestSkill_Create(t *testing.T) {
 
 func TestWeaponSkill_Create(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	testDefinition := []struct {
 		name        string
 		weaponSkill *models.WeaponSkill
@@ -90,7 +100,7 @@ func TestWeaponSkill_Create(t *testing.T) {
 				return
 			}
 			assert.NoError(t, err)
-			assert.Equal(t, "midgard", tt.weaponSkill.GameSystem)
+			assert.Equal(t, gs.ID, tt.weaponSkill.GameSystemId)
 			assert.NotZero(t, tt.weaponSkill.GameSystemId)
 			assert.NotZero(t, tt.weaponSkill.ID)
 		})
@@ -108,6 +118,7 @@ func TestSkill_TableName(t *testing.T) {
 
 func TestSkill_First(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	testDefinition := []struct {
 		name     string
 		skill    *models.Skill
@@ -155,7 +166,7 @@ func TestSkill_First(t *testing.T) {
 
 			assert.NoError(t, err)
 			assert.Equal(t, tt.skill.Name, s.Name)
-			assert.Equal(t, "midgard", s.GameSystem)
+			assert.Equal(t, gs.ID, s.GameSystemId)
 			assert.NotZero(t, s.GameSystemId)
 		})
 	}
@@ -164,6 +175,7 @@ func TestSkill_First(t *testing.T) {
 
 func TestSkill_FirstId(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	testDefinition := []struct {
 		name    string
 		skill   *models.Skill
@@ -212,7 +224,7 @@ func TestSkill_FirstId(t *testing.T) {
 
 			assert.NoError(t, err)
 			assert.Equal(t, tt.skill.Name, s.Name)
-			assert.Equal(t, "midgard", s.GameSystem)
+			assert.Equal(t, gs.ID, s.GameSystemId)
 			assert.NotZero(t, s.GameSystemId)
 			assert.Equal(t, tt.findId, s.ID)
 		})
@@ -232,7 +244,7 @@ func TestSkill_Save(t *testing.T) {
 			skill: &models.Skill{
 				Name:         "Test Skill",
 				Beschreibung: "Original Description",
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 			},
 			wantErr: false,
 		},
diff --git a/backend/gsmaster/learning_costs_migration.go b/backend/gsmaster/learning_costs_migration.go
index 7f2067d..47ca3cd 100644
--- a/backend/gsmaster/learning_costs_migration.go
+++ b/backend/gsmaster/learning_costs_migration.go
@@ -74,46 +74,46 @@ func MigrateLearningCostsToDatabase() error {
 func migrateSources() error {
 	sources := []models.Source{
 		{
-			Code:        "KOD",
-			Name:        "Kodex",
-			FullName:    "Midgard Regelwerk - Kodex",
-			Edition:     "5. Edition",
-			Publisher:   "Pegasus Spiele",
-			IsCore:      true,
-			IsActive:    true,
-			GameSystem:  "midgard",
-			Description: "Grundregelwerk für Midgard",
+			Code:         "KOD",
+			Name:         "Kodex",
+			FullName:     "Midgard Regelwerk - Kodex",
+			Edition:      "5. Edition",
+			Publisher:    "Pegasus Spiele",
+			IsCore:       true,
+			IsActive:     true,
+			GameSystemId: 1,
+			Description:  "Grundregelwerk für Midgard",
 		},
 		{
-			Code:        "ARK",
-			Name:        "Arkanum",
-			FullName:    "Midgard Arkanum",
-			Edition:     "5. Edition",
-			Publisher:   "Pegasus Spiele",
-			IsCore:      false,
-			IsActive:    true,
-			GameSystem:  "midgard",
-			Description: "Erweiterungsregelwerk für Zauber und Magie",
+			Code:         "ARK",
+			Name:         "Arkanum",
+			FullName:     "Midgard Arkanum",
+			Edition:      "5. Edition",
+			Publisher:    "Pegasus Spiele",
+			IsCore:       false,
+			IsActive:     true,
+			GameSystemId: 1,
+			Description:  "Erweiterungsregelwerk für Zauber und Magie",
 		},
 		{
-			Code:        "MYS",
-			Name:        "Mysterium",
-			FullName:    "Midgard Mysterium",
-			Edition:     "5. Edition",
-			Publisher:   "Pegasus Spiele",
-			IsCore:      false,
-			IsActive:    true,
-			GameSystem:  "midgard",
-			Description: "Erweiterungsregelwerk für Geheimnisse und Mysterien",
+			Code:         "MYS",
+			Name:         "Mysterium",
+			FullName:     "Midgard Mysterium",
+			Edition:      "5. Edition",
+			Publisher:    "Pegasus Spiele",
+			IsCore:       false,
+			IsActive:     true,
+			GameSystemId: 1,
+			Description:  "Erweiterungsregelwerk für Geheimnisse und Mysterien",
 		},
 		{
-			Code:        "UNB",
-			Name:        "Unbekannt",
-			FullName:    "Unbekannte Quelle",
-			IsCore:      false,
-			IsActive:    true,
-			GameSystem:  "midgard",
-			Description: "Für Inhalte ohne bekannte Quelle",
+			Code:         "UNB",
+			Name:         "Unbekannt",
+			FullName:     "Unbekannte Quelle",
+			IsCore:       false,
+			IsActive:     true,
+			GameSystemId: 1,
+			Description:  "Für Inhalte ohne bekannte Quelle",
 		},
 	}
 
diff --git a/backend/gsmaster/lernkosten_maps_test.go b/backend/gsmaster/lernkosten_maps_test.go
index b62ac15..5e47e3f 100644
--- a/backend/gsmaster/lernkosten_maps_test.go
+++ b/backend/gsmaster/lernkosten_maps_test.go
@@ -144,7 +144,7 @@ func TestGetSpellInfo(t *testing.T) {
 	// Create minimal test spell data for our test
 	testSpells := []models.Spell{
 		{
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         "Schlummer",
 			Beschreibung: "Test spell for GetSpellInfo",
 			Quelle:       "Test",
@@ -152,7 +152,7 @@ func TestGetSpellInfo(t *testing.T) {
 			Category:     "Beherrschen",
 		},
 		{
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         "Erkennen von Krankheit",
 			Beschreibung: "Test spell for GetSpellInfo",
 			Quelle:       "Test",
@@ -160,7 +160,7 @@ func TestGetSpellInfo(t *testing.T) {
 			Category:     "Dweomerzauber",
 		},
 		{
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         "Das Loblied",
 			Beschreibung: "Test spell for GetSpellInfo",
 			Quelle:       "Test",
diff --git a/backend/gsmaster/skill_create_test.go b/backend/gsmaster/skill_create_test.go
index 4b5d3a3..7303838 100644
--- a/backend/gsmaster/skill_create_test.go
+++ b/backend/gsmaster/skill_create_test.go
@@ -19,7 +19,7 @@ func TestCreateSkillWithCategories(t *testing.T) {
 	req := SkillUpdateRequest{
 		Skill: models.Skill{
 			Name:             "Neue Fertigkeit",
-			GameSystem:       "midgard",
+			GameSystemId:     1,
 			Beschreibung:     "Test Fertigkeit",
 			Initialwert:      5,
 			BasisWert:        0,
@@ -94,11 +94,11 @@ func TestCreateSkillWithMultipleCategories(t *testing.T) {
 	// Prepare create request with multiple categories
 	req := SkillUpdateRequest{
 		Skill: models.Skill{
-			Name:        "Multi-Kategorie Fertigkeit",
-			GameSystem:  "midgard",
-			Initialwert: 10,
-			Improvable:  true,
-			SourceID:    source.ID,
+			Name:         "Multi-Kategorie Fertigkeit",
+			GameSystemId: 1,
+			Initialwert:  10,
+			Improvable:   true,
+			SourceID:     source.ID,
 		},
 		CategoryDifficulties: []CategoryDifficultyPair{
 			{
@@ -136,8 +136,8 @@ func TestCreateSkillValidation(t *testing.T) {
 	// Test creating skill without name
 	req := SkillUpdateRequest{
 		Skill: models.Skill{
-			GameSystem:  "midgard",
-			Initialwert: 5,
+			GameSystemId: 1,
+			Initialwert:  5,
 		},
 		CategoryDifficulties: []CategoryDifficultyPair{},
 	}
diff --git a/backend/gsmaster/skill_enhanced_handlers_test.go b/backend/gsmaster/skill_enhanced_handlers_test.go
index 1cb0f92..517dfe0 100644
--- a/backend/gsmaster/skill_enhanced_handlers_test.go
+++ b/backend/gsmaster/skill_enhanced_handlers_test.go
@@ -70,7 +70,7 @@ func TestGetSkillWithCategories(t *testing.T) {
 
 	skill := models.Skill{
 		Name:             "TestSchwimmen",
-		GameSystem:       "midgard",
+		GameSystemId: 1,
 		Initialwert:      12,
 		Improvable:       true,
 		Bonuseigenschaft: "Gw",
@@ -127,7 +127,7 @@ func TestGetSkillWithCategories_MultipleCategories(t *testing.T) {
 
 	skill := models.Skill{
 		Name:             "TestReiten",
-		GameSystem:       "midgard",
+		GameSystemId: 1,
 		Initialwert:      5,
 		Improvable:       true,
 		Bonuseigenschaft: "Gw",
@@ -201,7 +201,7 @@ func TestUpdateSkillWithCategories(t *testing.T) {
 
 	skill := models.Skill{
 		Name:             "TestKlettern",
-		GameSystem:       "midgard",
+		GameSystemId: 1,
 		Initialwert:      10,
 		Improvable:       true,
 		Bonuseigenschaft: "Gw",
@@ -230,7 +230,7 @@ func TestUpdateSkillWithCategories(t *testing.T) {
 		Skill: models.Skill{
 			ID:               skill.ID,
 			Name:             "TestKlettern",
-			GameSystem:       "midgard",
+			GameSystemId: 1,
 			Initialwert:      12, // Changed
 			Improvable:       true,
 			Bonuseigenschaft: "St", // Changed
@@ -300,7 +300,7 @@ func TestUpdateSkillBooleanFields(t *testing.T) {
 	source := getOrCreateSource("TSTBOOL", "TestBoolean")
 	skill := models.Skill{
 		Name:        "TestBooleanSkill",
-		GameSystem:  "midgard",
+		GameSystemId: 1,
 		Initialwert: 5,
 		Improvable:  true,
 		InnateSkill: false,
@@ -326,7 +326,7 @@ func TestUpdateSkillBooleanFields(t *testing.T) {
 		Skill: models.Skill{
 			ID:          skill.ID,
 			Name:        "TestBooleanSkill",
-			GameSystem:  "midgard",
+			GameSystemId: 1,
 			Initialwert: 5,
 			Improvable:  false, // Change to false
 			InnateSkill: true,  // Change to true
diff --git a/backend/importer/importJSON2ImportStruct_test.go b/backend/importer/importJSON2ImportStruct_test.go
index 5ebfa7b..09447b1 100644
--- a/backend/importer/importJSON2ImportStruct_test.go
+++ b/backend/importer/importJSON2ImportStruct_test.go
@@ -201,6 +201,7 @@ func TestImportVTTStructure(t *testing.T) {
 func TestImportSkill2GSMaster(t *testing.T) {
 
 	database.SetupTestDB(true)
+	gs := defaultGameSystem(t)
 
 	fileName := fmt.Sprintf("../testdata/%s", "VTT_Import1.json")
 	character, err := readImportChar(fileName)
@@ -216,7 +217,7 @@ func TestImportSkill2GSMaster(t *testing.T) {
 	assert.Equal(t, "check", skill.Bonuseigenschaft)
 	assert.Equal(t, "KOD5 99", skill.Quelle)
 	assert.Equal(t, false, skill.Improvable)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, gs.ID, skill.GameSystemId)
 	//}
 	skill2 := models.Skill{}
 	erro = skill2.First("Hören")
@@ -235,7 +236,7 @@ func TestImportSkill2GSMaster(t *testing.T) {
 	assert.Equal(t, skill2.Bonuseigenschaft, skill3.Bonuseigenschaft)
 	assert.Equal(t, skill2.Quelle, skill3.Quelle)
 	assert.Equal(t, skill2.Improvable, skill3.Improvable)
-	assert.Equal(t, skill2.GameSystem, skill3.GameSystem)
+	assert.Equal(t, skill2.GameSystemId, skill3.GameSystemId)
 
 	err = CheckFertigkeiten2GSMaster(character.Fertigkeiten)
 	assert.NoError(t, err, "Expected no error when checkimg Skills against gsmaster")
@@ -243,6 +244,7 @@ func TestImportSkill2GSMaster(t *testing.T) {
 
 func TestImportWeaponSkill2GSMaster(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	defer database.ResetTestDB()
 	// Clear weapon skills to test actual import, not pre-existing data
 	database.DB.Exec("DELETE FROM gsm_weaponskills")
@@ -261,7 +263,7 @@ func TestImportWeaponSkill2GSMaster(t *testing.T) {
 	assert.Equal(t, "check", skill.Bonuseigenschaft)
 	assert.Equal(t, "KOD5 144", skill.Quelle)
 	assert.Equal(t, true, skill.Improvable)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, gs.ID, skill.GameSystemId)
 	//}
 	skill2 := models.WeaponSkill{}
 	erro = skill2.First("Armbrüste")
@@ -280,7 +282,7 @@ func TestImportWeaponSkill2GSMaster(t *testing.T) {
 	assert.Equal(t, skill2.Bonuseigenschaft, skill3.Bonuseigenschaft)
 	assert.Equal(t, skill2.Quelle, skill3.Quelle)
 	assert.Equal(t, skill2.Improvable, skill3.Improvable)
-	assert.Equal(t, skill2.GameSystem, skill3.GameSystem)
+	assert.Equal(t, skill2.GameSystemId, skill3.GameSystemId)
 
 	err = CheckWaffenFertigkeiten2GSMaster(character.Waffenfertigkeiten)
 	assert.NoError(t, err, "Expected no error when checkimg WeaponSkills against gsmaster")
@@ -288,6 +290,7 @@ func TestImportWeaponSkill2GSMaster(t *testing.T) {
 
 func TestImportSpell2GSMaster(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	fileName := fmt.Sprintf("../testdata/%s", "VTT_Import1.json")
 	character, err := readImportChar(fileName)
 	assert.NoError(t, err, "Expected no error when Unmarshal filecontent")
@@ -296,7 +299,7 @@ func TestImportSpell2GSMaster(t *testing.T) {
 
 	assert.NoError(t, erro, "Expected no error when Unmarshal filecontent")
 	assert.GreaterOrEqual(t, int(skill.ID), 1)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, gs.ID, skill.GameSystemId)
 	assert.Equal(t, "Angst", skill.Name)
 	assert.Equal(t, "", skill.Beschreibung)
 	assert.Equal(t, "ARK", skill.Quelle)
@@ -316,7 +319,7 @@ func TestImportSpell2GSMaster(t *testing.T) {
 	assert.Equal(t, "Angst", skill3.Name)
 
 	assert.Equal(t, skill2.ID, skill3.ID)
-	assert.Equal(t, skill2.GameSystem, skill3.GameSystem)
+	assert.Equal(t, skill2.GameSystemId, skill3.GameSystemId)
 	assert.Equal(t, skill2.Name, skill3.Name)
 	assert.Equal(t, skill2.Beschreibung, skill3.Beschreibung)
 	assert.Equal(t, skill2.Quelle, skill3.Quelle)
@@ -331,6 +334,7 @@ func TestImportSpell2GSMaster(t *testing.T) {
 
 func TestImportWeapon2GSMaster(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	defer database.ResetTestDB()
 	// Clear weapons to test actual import, not pre-existing data
 	database.DB.Exec("DELETE FROM gsm_weapons")
@@ -343,7 +347,7 @@ func TestImportWeapon2GSMaster(t *testing.T) {
 
 	assert.NoError(t, erro, "Expected no error when Unmarshal filecontent")
 	assert.GreaterOrEqual(t, int(skill.ID), 1)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, gs.ID, skill.GameSystemId)
 	assert.Equal(t, "Armbrust:schwer", skill.Name)
 	assert.Equal(t, "", skill.Beschreibung)
 	assert.Equal(t, "", skill.Quelle)
@@ -363,7 +367,7 @@ func TestImportWeapon2GSMaster(t *testing.T) {
 	assert.Equal(t, "Armbrust:schwer", skill3.Name)
 
 	assert.Equal(t, skill2.ID, skill3.ID)
-	assert.Equal(t, skill2.GameSystem, skill3.GameSystem)
+	assert.Equal(t, skill2.GameSystemId, skill3.GameSystemId)
 	assert.Equal(t, skill2.Name, skill3.Name)
 	assert.Equal(t, skill2.Beschreibung, skill3.Beschreibung)
 	assert.Equal(t, skill2.Quelle, skill3.Quelle)
@@ -378,6 +382,7 @@ func TestImportWeapon2GSMaster(t *testing.T) {
 
 func TestImportContainer2GSMaster(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	fileName := fmt.Sprintf("../testdata/%s", "VTT_Import1.json")
 	character, err := readImportChar(fileName)
 	assert.NoError(t, err, "Expected no error when Unmarshal filecontent")
@@ -386,7 +391,7 @@ func TestImportContainer2GSMaster(t *testing.T) {
 
 	assert.NoError(t, erro, "Expected no error when Unmarshal filecontent")
 	assert.GreaterOrEqual(t, int(container.ID), 1)
-	assert.Equal(t, "midgard", container.GameSystem)
+	assert.Equal(t, gs.ID, container.GameSystemId)
 	assert.Equal(t, "Lederrucksack", container.Name)
 	assert.Equal(t, "für 25 kg", container.Beschreibung)
 	assert.Equal(t, "", container.Quelle)
@@ -406,7 +411,7 @@ func TestImportContainer2GSMaster(t *testing.T) {
 	assert.Equal(t, "Lederrucksack", container3.Name)
 
 	assert.Equal(t, container2.ID, container3.ID)
-	assert.Equal(t, container2.GameSystem, container3.GameSystem)
+	assert.Equal(t, container2.GameSystemId, container3.GameSystemId)
 	assert.Equal(t, container2.Name, container3.Name)
 	assert.Equal(t, container2.Beschreibung, container3.Beschreibung)
 	assert.Equal(t, container2.Quelle, container3.Quelle)
@@ -421,6 +426,7 @@ func TestImportContainer2GSMaster(t *testing.T) {
 
 func TestImportTransportation2GSMaster(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	fileName := fmt.Sprintf("../testdata/%s", "VTT_Import1.json")
 	character, err := readImportChar(fileName)
 	assert.NoError(t, err, "Expected no error when Unmarshal filecontent")
@@ -429,7 +435,7 @@ func TestImportTransportation2GSMaster(t *testing.T) {
 
 	assert.NoError(t, erro, "Expected no error when Unmarshal filecontent")
 	assert.GreaterOrEqual(t, int(skill.ID), 1)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, gs.ID, skill.GameSystemId)
 	assert.Equal(t, "Karren", skill.Name)
 	assert.Equal(t, "für 250 kg", skill.Beschreibung)
 	assert.Equal(t, "", skill.Quelle)
@@ -449,7 +455,7 @@ func TestImportTransportation2GSMaster(t *testing.T) {
 	assert.Equal(t, "Karren", skill3.Name)
 
 	assert.Equal(t, skill2.ID, skill3.ID)
-	assert.Equal(t, skill2.GameSystem, skill3.GameSystem)
+	assert.Equal(t, skill2.GameSystemId, skill3.GameSystemId)
 	assert.Equal(t, skill2.Name, skill3.Name)
 	assert.Equal(t, skill2.Beschreibung, skill3.Beschreibung)
 	assert.Equal(t, skill2.Quelle, skill3.Quelle)
@@ -464,6 +470,7 @@ func TestImportTransportation2GSMaster(t *testing.T) {
 
 func TestImportEquipment2GSMaster(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	fileName := fmt.Sprintf("../testdata/%s", "VTT_Import1.json")
 	character, err := readImportChar(fileName)
 	assert.NoError(t, err, "Expected no error when Unmarshal filecontent")
@@ -472,7 +479,7 @@ func TestImportEquipment2GSMaster(t *testing.T) {
 
 	assert.NoError(t, erro, "Expected no error when Unmarshal filecontent")
 	assert.GreaterOrEqual(t, int(skill.ID), 1)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, gs.ID, skill.GameSystemId)
 	assert.Equal(t, "Lederrüstung", skill.Name)
 	assert.Equal(t, "", skill.Beschreibung)
 	assert.Equal(t, "", skill.Quelle)
@@ -490,7 +497,7 @@ func TestImportEquipment2GSMaster(t *testing.T) {
 	assert.Equal(t, "Lederrüstung", skill3.Name)
 
 	assert.Equal(t, skill2.ID, skill3.ID)
-	assert.Equal(t, skill2.GameSystem, skill3.GameSystem)
+	assert.Equal(t, skill2.GameSystemId, skill3.GameSystemId)
 	assert.Equal(t, skill2.Name, skill3.Name)
 	assert.Equal(t, skill2.Beschreibung, skill3.Beschreibung)
 	assert.Equal(t, skill2.Quelle, skill3.Quelle)
@@ -502,6 +509,7 @@ func TestImportEquipment2GSMaster(t *testing.T) {
 }
 func TestImportBelieve2GSMaster(t *testing.T) {
 	database.SetupTestDB()
+	gs := defaultGameSystem(t)
 	fileName := fmt.Sprintf("../testdata/%s", "VTT_Import1.json")
 	character, err := readImportChar(fileName)
 	assert.NoError(t, err, "Expected no error when Unmarshal filecontent")
@@ -510,7 +518,7 @@ func TestImportBelieve2GSMaster(t *testing.T) {
 
 	assert.NoError(t, erro, "Expected no error when Unmarshal filecontent")
 	assert.GreaterOrEqual(t, int(skill.ID), 1)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, gs.ID, skill.GameSystemId)
 	assert.Equal(t, "Torkin", skill.Name)
 	assert.Equal(t, "", skill.Beschreibung)
 	assert.Equal(t, "", skill.Quelle)
@@ -526,7 +534,7 @@ func TestImportBelieve2GSMaster(t *testing.T) {
 	assert.Equal(t, "Torkin", skill3.Name)
 
 	assert.Equal(t, skill2.ID, skill3.ID)
-	assert.Equal(t, skill2.GameSystem, skill3.GameSystem)
+	assert.Equal(t, skill2.GameSystemId, skill3.GameSystemId)
 	assert.Equal(t, skill2.Name, skill3.Name)
 	assert.Equal(t, skill2.Beschreibung, skill3.Beschreibung)
 	assert.Equal(t, skill2.Quelle, skill3.Quelle)
diff --git a/backend/importer/importer_test.go b/backend/importer/importer_test.go
index adef72c..55cbe9a 100644
--- a/backend/importer/importer_test.go
+++ b/backend/importer/importer_test.go
@@ -14,8 +14,16 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
+func defaultGameSystem(t *testing.T) *models.GameSystem {
+	gs := models.GetGameSystem(0, "midgard")
+	require.NotNil(t, gs)
+	require.NotZero(t, gs.ID)
+	return gs
+}
+
 func NoT_estImportCsv2Spell(t *testing.T) {
 	// Clear source cache to ensure clean test state
 	ClearSourceCache()
@@ -102,7 +110,7 @@ func NoT_estImportCsv2Spell(t *testing.T) {
 	t.Run("Test update existing spell", func(t *testing.T) {
 		// Create a test spell first
 		testSpell := models.Spell{
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         "Test Zauber",
 			Beschreibung: "Original description",
 			Stufe:        1,
@@ -135,6 +143,7 @@ Test Zauber,Updated description,2`
 	})
 
 	t.Run("Test source lookup function", func(t *testing.T) {
+		gs := defaultGameSystem(t)
 		// Clear cache to ensure fresh lookups
 		ClearSourceCache()
 
@@ -154,7 +163,7 @@ Test Zauber,Updated description,2`
 		assert.NoError(t, err, "Should find newly created source")
 		assert.Equal(t, "NEWCODE", newSource.Code, "Source code should match")
 		assert.Equal(t, "NEWCODE", newSource.Name, "Source name should default to code")
-		assert.Equal(t, "midgard", newSource.GameSystem, "Game system should be midgard")
+		assert.Equal(t, gs.ID, newSource.GameSystemId, "Game system ID should match default")
 		assert.True(t, newSource.IsActive, "New source should be active")
 
 		// Test that the second lookup uses cache (should return same ID)
diff --git a/backend/maintenance/skill_migration_test.go b/backend/maintenance/skill_migration_test.go
index 0d67de9..64a9501 100644
--- a/backend/maintenance/skill_migration_test.go
+++ b/backend/maintenance/skill_migration_test.go
@@ -49,7 +49,7 @@ func TestMigrateSkillCategoriesToRelations(t *testing.T) {
 			Name:             "TestMigSkill_Schwimmen",
 			Category:         "Körper",
 			Difficulty:       "leicht",
-			GameSystem:       "midgard",
+			GameSystemId: 1,
 			Initialwert:      12,
 			Improvable:       true,
 			Bonuseigenschaft: "Gw",
@@ -59,7 +59,7 @@ func TestMigrateSkillCategoriesToRelations(t *testing.T) {
 			Name:             "TestMigSkill_Klettern",
 			Category:         "Körper",
 			Difficulty:       "normal",
-			GameSystem:       "midgard",
+			GameSystemId: 1,
 			Initialwert:      10,
 			Improvable:       true,
 			Bonuseigenschaft: "Gw",
@@ -69,7 +69,7 @@ func TestMigrateSkillCategoriesToRelations(t *testing.T) {
 			Name:             "TestMigSkill_LesenSchreiben",
 			Category:         "Wissen",
 			Difficulty:       "schwer",
-			GameSystem:       "midgard",
+			GameSystemId: 1,
 			Initialwert:      0,
 			Improvable:       true,
 			Bonuseigenschaft: "In",
@@ -190,7 +190,7 @@ func TestMigrateSkillCategoryDifficulty_NoCategory(t *testing.T) {
 		Name:        "TestMigSkill_NoCategory",
 		Category:    "", // Empty category
 		Difficulty:  "", // Empty difficulty
-		GameSystem:  "midgard",
+		GameSystemId: 1,
 		Initialwert: 10,
 		SourceID:    source.ID,
 	}
diff --git a/backend/models/database_test.go b/backend/models/database_test.go
index 85ab956..f1828c9 100644
--- a/backend/models/database_test.go
+++ b/backend/models/database_test.go
@@ -369,12 +369,12 @@ func TestMigrationWorkflow_StructureIntegrity(t *testing.T) {
 
 	// Test gsmaster category with a skill
 	testSkill := &Skill{
-		GameSystem:  "midgard",
-		Name:        "Test Skill",
-		Category:    "Test Category",
-		Difficulty:  "normal",
-		Initialwert: 5,
-		Improvable:  true,
+		GameSystemId: 1,
+		Name:         "Test Skill",
+		Category:     "Test Category",
+		Difficulty:   "normal",
+		Initialwert:  5,
+		Improvable:   true,
 	}
 	err = database.DB.Create(testSkill).Error
 	assert.NoError(t, err, "Should be able to create a skill")
diff --git a/backend/models/model_char_skills_test.go b/backend/models/model_char_skills_test.go
index 0b6563e..9345696 100644
--- a/backend/models/model_char_skills_test.go
+++ b/backend/models/model_char_skills_test.go
@@ -18,7 +18,7 @@ func setupTestDB(t *testing.T) {
 
 func createTestSkill(name string) *Skill {
 	return &Skill{
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Name:             name,
 		Beschreibung:     "Test skill description",
 		Category:         "Körper",
@@ -342,7 +342,7 @@ func TestSkillStructures_WithDatabase(t *testing.T) {
 
 	weaponSkillData := WeaponSkill{
 		Skill: Skill{
-			GameSystem:       "midgard",
+			GameSystemId:     1,
 			Name:             "Bögen",
 			Beschreibung:     "Bow skills",
 			Category:         "Fernkampf",
diff --git a/backend/models/model_gsmaster_basiswert_test.go b/backend/models/model_gsmaster_basiswert_test.go
index b968ce1..3e153d1 100644
--- a/backend/models/model_gsmaster_basiswert_test.go
+++ b/backend/models/model_gsmaster_basiswert_test.go
@@ -7,9 +7,9 @@ import (
 func TestSkillBasisWert(t *testing.T) {
 	// Test that BasisWert defaults to 0 in master skill data
 	skill := Skill{
-		Name:        "TestSkill",
-		GameSystem:  "midgard",
-		Initialwert: 5,
+		Name:         "TestSkill",
+		GameSystemId: 1,
+		Initialwert:  5,
 	}
 
 	// BasisWert should default to 0
@@ -21,10 +21,10 @@ func TestSkillBasisWert(t *testing.T) {
 func TestSkillBasisWertSet(t *testing.T) {
 	// Test that BasisWert can be set in master skill data
 	skill := Skill{
-		Name:        "TestSkill",
-		GameSystem:  "midgard",
-		Initialwert: 5,
-		BasisWert:   3,
+		Name:         "TestSkill",
+		GameSystemId: 1,
+		Initialwert:  5,
+		BasisWert:    3,
 	}
 
 	if skill.BasisWert != 3 {
@@ -36,10 +36,10 @@ func TestWeaponSkillBasisWert(t *testing.T) {
 	// Test that BasisWert works for WeaponSkill (inherited from Skill)
 	weaponSkill := WeaponSkill{
 		Skill: Skill{
-			Name:        "TestWeaponSkill",
-			GameSystem:  "midgard",
-			Initialwert: 5,
-			BasisWert:   2,
+			Name:         "TestWeaponSkill",
+			GameSystemId: 1,
+			Initialwert:  5,
+			BasisWert:    2,
 		},
 	}
 
diff --git a/backend/models/model_gsmaster_test.go b/backend/models/model_gsmaster_test.go
index d8945b2..fdc34c6 100644
--- a/backend/models/model_gsmaster_test.go
+++ b/backend/models/model_gsmaster_test.go
@@ -18,7 +18,7 @@ func setupGSMasterTestDB(t *testing.T) {
 
 func createTestGSMSkill(name string) *Skill {
 	return &Skill{
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Name:             name,
 		Beschreibung:     "Test skill description",
 		Category:         "Körper",
@@ -33,7 +33,7 @@ func createTestGSMSkill(name string) *Skill {
 func createTestWeaponSkill(name string) *WeaponSkill {
 	return &WeaponSkill{
 		Skill: Skill{
-			GameSystem:       "midgard",
+			GameSystemId:     1,
 			Name:             name,
 			Beschreibung:     "Test weapon skill description",
 			Category:         "Kampf",
@@ -48,7 +48,7 @@ func createTestWeaponSkill(name string) *WeaponSkill {
 
 func createTestSpell(name string) *Spell {
 	return &Spell{
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Name:             name,
 		Beschreibung:     "Test spell description",
 		Bonus:            0,
@@ -68,7 +68,7 @@ func createTestSpell(name string) *Spell {
 
 func createTestEquipment(name string) *Equipment {
 	return &Equipment{
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Name:         name,
 		Beschreibung: "Test equipment description",
 		Gewicht:      1.5,
@@ -80,7 +80,7 @@ func createTestEquipment(name string) *Equipment {
 func createTestWeapon(name string) *Weapon {
 	return &Weapon{
 		Equipment: Equipment{
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         name,
 			Beschreibung: "Test weapon description",
 			Gewicht:      2.0,
@@ -95,7 +95,7 @@ func createTestWeapon(name string) *Weapon {
 func createTestContainer(name string) *Container {
 	return &Container{
 		Equipment: Equipment{
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         name,
 			Beschreibung: "Test container description",
 			Gewicht:      0.5,
@@ -109,7 +109,7 @@ func createTestContainer(name string) *Container {
 
 func createTestBelieve(name string) *Believe {
 	return &Believe{
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Name:         name,
 		Beschreibung: "Test believe description",
 		SourceID:     1, // Use active source KOD
@@ -169,7 +169,7 @@ func TestSkill_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, skill.ID)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, uint(1), skill.GameSystemId)
 }
 
 func TestSkill_First_Success(t *testing.T) {
@@ -186,7 +186,7 @@ func TestSkill_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstSkill", foundSkill.Name)
-	assert.Equal(t, "midgard", foundSkill.GameSystem)
+	assert.Equal(t, uint(1), foundSkill.GameSystemId)
 }
 
 func TestSkill_First_NotFound(t *testing.T) {
@@ -374,7 +374,7 @@ func TestWeaponSkill_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, weaponSkill.ID)
-	assert.Equal(t, "midgard", weaponSkill.GameSystem)
+	assert.Equal(t, uint(1), weaponSkill.GameSystemId)
 }
 
 func TestWeaponSkill_First_Success(t *testing.T) {
@@ -391,7 +391,7 @@ func TestWeaponSkill_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstWeaponSkill", foundWeaponSkill.Name)
-	assert.Equal(t, "midgard", foundWeaponSkill.GameSystem)
+	assert.Equal(t, uint(1), foundWeaponSkill.GameSystemId)
 }
 
 func TestWeaponSkill_First_NotFound(t *testing.T) {
@@ -459,7 +459,7 @@ func TestSpell_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, spell.ID)
-	assert.Equal(t, "midgard", spell.GameSystem)
+	assert.Equal(t, uint(1), spell.GameSystemId)
 }
 
 func TestSpell_First_Success(t *testing.T) {
@@ -476,7 +476,7 @@ func TestSpell_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstSpell", foundSpell.Name)
-	assert.Equal(t, "midgard", foundSpell.GameSystem)
+	assert.Equal(t, uint(1), foundSpell.GameSystemId)
 }
 
 func TestSpell_First_NotFound(t *testing.T) {
@@ -616,7 +616,7 @@ func TestEquipment_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, equipment.ID)
-	assert.Equal(t, "midgard", equipment.GameSystem)
+	assert.Equal(t, uint(1), equipment.GameSystemId)
 }
 
 func TestEquipment_First_Success(t *testing.T) {
@@ -633,7 +633,7 @@ func TestEquipment_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstEquipment", foundEquipment.Name)
-	assert.Equal(t, "midgard", foundEquipment.GameSystem)
+	assert.Equal(t, uint(1), foundEquipment.GameSystemId)
 }
 
 func TestEquipment_First_NotFound(t *testing.T) {
@@ -695,8 +695,8 @@ func TestEquipment_Create_SetsDefaultGameSystem(t *testing.T) {
 
 	err := equipment.Create()
 	require.NoError(t, err)
-	assert.Equal(t, "midgard", equipment.GameSystem)
-	assert.NotZero(t, equipment.GameSystemId)
+	assert.Equal(t, uint(1), equipment.GameSystemId)
+	assert.NotEmpty(t, equipment.GameSystem)
 }
 
 func TestEquipment_First_UsesGameSystemId(t *testing.T) {
@@ -745,7 +745,7 @@ func TestWeapon_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, weapon.ID)
-	assert.Equal(t, "midgard", weapon.GameSystem)
+	assert.Equal(t, uint(1), weapon.GameSystemId)
 }
 
 func TestWeapon_Create_SetsDefaultGameSystem(t *testing.T) {
@@ -765,8 +765,8 @@ func TestWeapon_Create_SetsDefaultGameSystem(t *testing.T) {
 
 	err := weapon.Create()
 	require.NoError(t, err)
-	assert.Equal(t, "midgard", weapon.GameSystem)
-	assert.NotZero(t, weapon.GameSystemId)
+	assert.Equal(t, uint(1), weapon.GameSystemId)
+	assert.NotEmpty(t, weapon.GameSystem)
 }
 
 func TestWeapon_First_Success(t *testing.T) {
@@ -783,7 +783,7 @@ func TestWeapon_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstWeapon", foundWeapon.Name)
-	assert.Equal(t, "midgard", foundWeapon.GameSystem)
+	assert.Equal(t, uint(1), foundWeapon.GameSystemId)
 }
 
 func TestWeapon_First_NotFound(t *testing.T) {
@@ -838,7 +838,7 @@ func TestWeapon_RangedWeaponRanges(t *testing.T) {
 	// Create a ranged weapon with ranges
 	weapon := &Weapon{
 		Equipment: Equipment{
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         "TestBogen",
 			Beschreibung: "Test ranged weapon",
 			Gewicht:      1.5,
@@ -920,7 +920,7 @@ func TestContainer_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, container.ID)
-	assert.Equal(t, "midgard", container.GameSystem)
+	assert.Equal(t, uint(1), container.GameSystemId)
 }
 
 func TestContainer_First_Success(t *testing.T) {
@@ -937,7 +937,7 @@ func TestContainer_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstContainer", foundContainer.Name)
-	assert.Equal(t, "midgard", foundContainer.GameSystem)
+	assert.Equal(t, uint(1), foundContainer.GameSystemId)
 }
 
 func TestContainer_First_NotFound(t *testing.T) {
@@ -1003,8 +1003,8 @@ func TestContainer_Create_SetsDefaultGameSystem(t *testing.T) {
 
 	err := container.Create()
 	require.NoError(t, err)
-	assert.Equal(t, "midgard", container.GameSystem)
-	assert.NotZero(t, container.GameSystemId)
+	assert.Equal(t, uint(1), container.GameSystemId)
+	assert.NotEmpty(t, container.GameSystem)
 }
 
 // =============================================================================
@@ -1024,7 +1024,7 @@ func TestTransportation_Create(t *testing.T) {
 	transportation := &Transportation{
 		Container: Container{
 			Equipment: Equipment{
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 				Name:         "TestCreateTransportation",
 				Beschreibung: "Test transportation description",
 				Gewicht:      100.0,
@@ -1039,7 +1039,7 @@ func TestTransportation_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, transportation.ID)
-	assert.Equal(t, "midgard", transportation.GameSystem)
+	assert.Equal(t, uint(1), transportation.GameSystemId)
 }
 
 func TestTransportation_First_Success(t *testing.T) {
@@ -1049,7 +1049,7 @@ func TestTransportation_First_Success(t *testing.T) {
 	testTransportation := &Transportation{
 		Container: Container{
 			Equipment: Equipment{
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 				Name:         "TestFirstTransportation",
 				Beschreibung: "Test transportation description",
 				Gewicht:      100.0,
@@ -1069,7 +1069,7 @@ func TestTransportation_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstTransportation", foundTransportation.Name)
-	assert.Equal(t, "midgard", foundTransportation.GameSystem)
+	assert.Equal(t, uint(1), foundTransportation.GameSystemId)
 }
 
 func TestTransportation_FirstId_Success(t *testing.T) {
@@ -1079,7 +1079,7 @@ func TestTransportation_FirstId_Success(t *testing.T) {
 	testTransportation := &Transportation{
 		Container: Container{
 			Equipment: Equipment{
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 				Name:         "TestFirstIdTransportation",
 				Beschreibung: "Test transportation description",
 				Gewicht:      100.0,
@@ -1108,7 +1108,7 @@ func TestTransportation_Save(t *testing.T) {
 	transportation := &Transportation{
 		Container: Container{
 			Equipment: Equipment{
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 				Name:         "TestSaveTransportation",
 				Beschreibung: "Test transportation description",
 				Gewicht:      100.0,
@@ -1154,8 +1154,8 @@ func TestTransportation_Create_SetsDefaultGameSystem(t *testing.T) {
 
 	err := transportation.Create()
 	require.NoError(t, err)
-	assert.Equal(t, "midgard", transportation.GameSystem)
-	assert.NotZero(t, transportation.GameSystemId)
+	assert.Equal(t, uint(1), transportation.GameSystemId)
+	assert.NotEmpty(t, transportation.GameSystem)
 }
 
 // =============================================================================
@@ -1177,7 +1177,7 @@ func TestBelieve_Create(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.NotZero(t, believe.ID)
-	assert.Equal(t, "midgard", believe.GameSystem)
+	assert.Equal(t, uint(1), believe.GameSystemId)
 }
 
 func TestBelieve_First_Success(t *testing.T) {
@@ -1194,7 +1194,7 @@ func TestBelieve_First_Success(t *testing.T) {
 
 	assert.NoError(t, err)
 	assert.Equal(t, "TestFirstBelieve", foundBelieve.Name)
-	assert.Equal(t, "midgard", foundBelieve.GameSystem)
+	assert.Equal(t, uint(1), foundBelieve.GameSystemId)
 }
 
 func TestBelieve_FirstId_Success(t *testing.T) {
@@ -1431,7 +1431,7 @@ func TestFirst_EmptyName_EdgeCases(t *testing.T) {
 func TestSkill_StructFieldValidation(t *testing.T) {
 	skill := Skill{
 		ID:               1,
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Name:             "TestSkill",
 		Beschreibung:     "Test description",
 		Quelle:           "Test source",
@@ -1446,7 +1446,7 @@ func TestSkill_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), skill.ID)
-	assert.Equal(t, "midgard", skill.GameSystem)
+	assert.Equal(t, uint(1), skill.GameSystemId)
 	assert.Equal(t, "TestSkill", skill.Name)
 	assert.Equal(t, "Test description", skill.Beschreibung)
 	assert.Equal(t, "Test source", skill.Quelle)
@@ -1464,7 +1464,7 @@ func TestWeaponSkill_StructFieldValidation(t *testing.T) {
 	weaponSkill := WeaponSkill{
 		Skill: Skill{
 			ID:               1,
-			GameSystem:       "midgard",
+			GameSystemId:     1,
 			Name:             "TestWeaponSkill",
 			Beschreibung:     "Test weapon skill description",
 			Category:         "Kampf",
@@ -1477,7 +1477,7 @@ func TestWeaponSkill_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), weaponSkill.ID)
-	assert.Equal(t, "midgard", weaponSkill.GameSystem)
+	assert.Equal(t, uint(1), weaponSkill.GameSystemId)
 	assert.Equal(t, "TestWeaponSkill", weaponSkill.Name)
 	assert.Equal(t, "Test weapon skill description", weaponSkill.Beschreibung)
 	assert.Equal(t, "Kampf", weaponSkill.Category)
@@ -1491,7 +1491,7 @@ func TestWeaponSkill_StructFieldValidation(t *testing.T) {
 func TestSpell_StructFieldValidation(t *testing.T) {
 	spell := Spell{
 		ID:               1,
-		GameSystem:       "midgard",
+		GameSystemId:     1,
 		Name:             "TestSpell",
 		Beschreibung:     "Test spell description",
 		Quelle:           "Test source",
@@ -1512,7 +1512,6 @@ func TestSpell_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), spell.ID)
-	assert.Equal(t, "midgard", spell.GameSystem)
 	assert.Equal(t, "TestSpell", spell.Name)
 	assert.Equal(t, "Test spell description", spell.Beschreibung)
 	assert.Equal(t, "Test source", spell.Quelle)
@@ -1530,12 +1529,13 @@ func TestSpell_StructFieldValidation(t *testing.T) {
 	assert.Equal(t, "elementar", spell.Ursprung)
 	assert.Equal(t, "Zerstören", spell.Category)
 	assert.Equal(t, "Spruch", spell.LearningCategory)
+	assert.Equal(t, uint(1), spell.GameSystemId)
 }
 
 func TestEquipment_StructFieldValidation(t *testing.T) {
 	equipment := Equipment{
 		ID:           1,
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Name:         "TestEquipment",
 		Beschreibung: "Test equipment description",
 		Quelle:       "Test source",
@@ -1547,7 +1547,6 @@ func TestEquipment_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), equipment.ID)
-	assert.Equal(t, "midgard", equipment.GameSystem)
 	assert.Equal(t, "TestEquipment", equipment.Name)
 	assert.Equal(t, "Test equipment description", equipment.Beschreibung)
 	assert.Equal(t, "Test source", equipment.Quelle)
@@ -1556,13 +1555,14 @@ func TestEquipment_StructFieldValidation(t *testing.T) {
 	assert.Equal(t, 2.5, equipment.Gewicht)
 	assert.Equal(t, 15.0, equipment.Wert)
 	assert.True(t, equipment.PersonalItem)
+	assert.Equal(t, uint(1), equipment.GameSystemId)
 }
 
 func TestWeapon_StructFieldValidation(t *testing.T) {
 	weapon := Weapon{
 		Equipment: Equipment{
 			ID:           1,
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         "TestWeapon",
 			Beschreibung: "Test weapon description",
 			Gewicht:      3.0,
@@ -1574,7 +1574,6 @@ func TestWeapon_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), weapon.ID)
-	assert.Equal(t, "midgard", weapon.GameSystem)
 	assert.Equal(t, "TestWeapon", weapon.Name)
 	assert.Equal(t, "Test weapon description", weapon.Beschreibung)
 	assert.Equal(t, 3.0, weapon.Gewicht)
@@ -1582,13 +1581,14 @@ func TestWeapon_StructFieldValidation(t *testing.T) {
 	assert.False(t, weapon.PersonalItem)
 	assert.Equal(t, "Einhandschwerter", weapon.SkillRequired)
 	assert.Equal(t, "1W8+3", weapon.Damage)
+	assert.Equal(t, uint(1), weapon.GameSystemId)
 }
 
 func TestContainer_StructFieldValidation(t *testing.T) {
 	container := Container{
 		Equipment: Equipment{
 			ID:           1,
-			GameSystem:   "midgard",
+			GameSystemId: 1,
 			Name:         "TestContainer",
 			Beschreibung: "Test container description",
 			Gewicht:      1.0,
@@ -1600,7 +1600,6 @@ func TestContainer_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), container.ID)
-	assert.Equal(t, "midgard", container.GameSystem)
 	assert.Equal(t, "TestContainer", container.Name)
 	assert.Equal(t, "Test container description", container.Beschreibung)
 	assert.Equal(t, 1.0, container.Gewicht)
@@ -1608,6 +1607,7 @@ func TestContainer_StructFieldValidation(t *testing.T) {
 	assert.False(t, container.PersonalItem)
 	assert.Equal(t, 15.0, container.Tragkraft)
 	assert.Equal(t, 30.0, container.Volumen)
+	assert.Equal(t, uint(1), container.GameSystemId)
 }
 
 func TestTransportation_StructFieldValidation(t *testing.T) {
@@ -1615,7 +1615,7 @@ func TestTransportation_StructFieldValidation(t *testing.T) {
 		Container: Container{
 			Equipment: Equipment{
 				ID:           1,
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 				Name:         "TestTransportation",
 				Beschreibung: "Test transportation description",
 				Gewicht:      150.0,
@@ -1628,7 +1628,6 @@ func TestTransportation_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), transportation.ID)
-	assert.Equal(t, "midgard", transportation.GameSystem)
 	assert.Equal(t, "TestTransportation", transportation.Name)
 	assert.Equal(t, "Test transportation description", transportation.Beschreibung)
 	assert.Equal(t, 150.0, transportation.Gewicht)
@@ -1636,12 +1635,13 @@ func TestTransportation_StructFieldValidation(t *testing.T) {
 	assert.False(t, transportation.PersonalItem)
 	assert.Equal(t, 300.0, transportation.Tragkraft)
 	assert.Equal(t, 600.0, transportation.Volumen)
+	assert.Equal(t, uint(1), transportation.GameSystemId)
 }
 
 func TestBelieve_StructFieldValidation(t *testing.T) {
 	believe := Believe{
 		ID:           1,
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Name:         "TestBelieve",
 		Beschreibung: "Test believe description",
 		Quelle:       "Test source",
@@ -1650,12 +1650,12 @@ func TestBelieve_StructFieldValidation(t *testing.T) {
 	}
 
 	assert.Equal(t, uint(1), believe.ID)
-	assert.Equal(t, "midgard", believe.GameSystem)
 	assert.Equal(t, "TestBelieve", believe.Name)
 	assert.Equal(t, "Test believe description", believe.Beschreibung)
 	assert.Equal(t, "Test source", believe.Quelle)
 	assert.Equal(t, uint(10), believe.SourceID)
 	assert.Equal(t, 42, believe.PageNumber)
+	assert.Equal(t, uint(1), believe.GameSystemId)
 }
 
 // =============================================================================
@@ -1800,7 +1800,6 @@ func TestGSMaster_EdgeCases(t *testing.T) {
 
 func TestLearnCost_StructFields(t *testing.T) {
 	learnCost := LearnCost{
-		GameSystem:   "midgard",
 		GameSystemId: 1,
 		Stufe:        3,
 		LE:           10,
@@ -1824,8 +1823,8 @@ func TestLearnCost_EnsureGameSystem_DefaultsToMidgard(t *testing.T) {
 	lc := LearnCost{}
 	lc.ensureGameSystem()
 
-	assert.Equal(t, "midgard", lc.GameSystem)
 	assert.NotZero(t, lc.GameSystemId)
+	assert.NotEmpty(t, lc.GameSystem)
 }
 
 func TestLearnCost_EnsureGameSystem_UsesProvidedGameSystem(t *testing.T) {
@@ -1847,10 +1846,10 @@ func TestSkill_Create_DefaultImprovable(t *testing.T) {
 
 	// Test 1: Create skill without setting Improvable or InnateSkill
 	skill1 := Skill{
-		Name:        "Test Skill Default",
-		GameSystem:  "midgard",
-		Category:    "test",
-		Initialwert: 5,
+		Name:         "Test Skill Default",
+		GameSystemId: 1,
+		Category:     "test",
+		Initialwert:  5,
 	}
 	err := skill1.Create()
 	require.NoError(t, err)
@@ -1864,12 +1863,12 @@ func TestSkill_Create_DefaultImprovable(t *testing.T) {
 
 	// Test 2: Create skill with explicit Improvable=false and InnateSkill=true
 	skill2 := Skill{
-		Name:        "Test Innate Skill",
-		GameSystem:  "midgard",
-		Category:    "test",
-		Initialwert: 5,
-		Improvable:  false,
-		InnateSkill: true,
+		Name:         "Test Innate Skill",
+		GameSystemId: 1,
+		Category:     "test",
+		Initialwert:  5,
+		Improvable:   false,
+		InnateSkill:  true,
 	}
 	err = skill2.Create()
 	require.NoError(t, err)
@@ -1883,12 +1882,12 @@ func TestSkill_Create_DefaultImprovable(t *testing.T) {
 
 	// Test 3: Create skill with explicit Improvable=true
 	skill3 := Skill{
-		Name:        "Test Explicit Improvable",
-		GameSystem:  "midgard",
-		Category:    "test",
-		Initialwert: 5,
-		Improvable:  true,
-		InnateSkill: false,
+		Name:         "Test Explicit Improvable",
+		GameSystemId: 1,
+		Category:     "test",
+		Initialwert:  5,
+		Improvable:   true,
+		InnateSkill:  false,
 	}
 	err = skill3.Create()
 	require.NoError(t, err)
@@ -1908,10 +1907,10 @@ func TestWeaponSkill_Create_DefaultImprovable(t *testing.T) {
 	// Test 1: Create weapon skill without setting Improvable or InnateSkill
 	weaponSkill := WeaponSkill{
 		Skill: Skill{
-			Name:        "Test Weapon Skill",
-			GameSystem:  "midgard",
-			Category:    "weapon",
-			Initialwert: 5,
+			Name:         "Test Weapon Skill",
+			GameSystemId: 1,
+			Category:     "weapon",
+			Initialwert:  5,
 		},
 	}
 	err := weaponSkill.Create()
diff --git a/backend/models/model_learning_costs_test.go b/backend/models/model_learning_costs_test.go
index 519a1b5..acf4fb6 100644
--- a/backend/models/model_learning_costs_test.go
+++ b/backend/models/model_learning_costs_test.go
@@ -17,6 +17,13 @@ func setupLearningCostsTestDB(t *testing.T) {
 	require.NoError(t, err, "Failed to migrate database structure")
 }
 
+func defaultGameSystem(t *testing.T) *GameSystem {
+	gs := GetGameSystem(0, "midgard")
+	require.NotNil(t, gs)
+	require.NotZero(t, gs.ID)
+	return gs
+}
+
 // =============================================================================
 // Tests for Source struct and methods
 // =============================================================================
@@ -67,6 +74,7 @@ func TestSource_FirstByName_NotFound(t *testing.T) {
 
 func TestSource_Create_SetsGameSystem(t *testing.T) {
 	setupLearningCostsTestDB(t)
+	gs := defaultGameSystem(t)
 
 	source := Source{
 		Code: "TGS1",
@@ -77,8 +85,8 @@ func TestSource_Create_SetsGameSystem(t *testing.T) {
 
 	require.NoError(t, err)
 	assert.NotZero(t, source.ID)
-	assert.Equal(t, "midgard", source.GameSystem)
-	assert.NotZero(t, source.GameSystemId)
+	assert.Equal(t, gs.Name, source.GameSystem)
+	assert.Equal(t, gs.ID, source.GameSystemId)
 }
 
 // =============================================================================
@@ -127,6 +135,7 @@ func TestCharacterClass_FirstByName_NotFound(t *testing.T) {
 
 func TestCharacterClass_Create_SetsGameSystem(t *testing.T) {
 	setupLearningCostsTestDB(t)
+	gs := defaultGameSystem(t)
 
 	var src Source
 	require.NoError(t, src.FirstByCode("KOD"))
@@ -141,8 +150,8 @@ func TestCharacterClass_Create_SetsGameSystem(t *testing.T) {
 
 	require.NoError(t, err)
 	assert.NotZero(t, class.ID)
-	assert.Equal(t, "midgard", class.GameSystem)
-	assert.NotZero(t, class.GameSystemId)
+	assert.Equal(t, gs.Name, class.GameSystem)
+	assert.Equal(t, gs.ID, class.GameSystemId)
 }
 
 // =============================================================================
@@ -170,6 +179,7 @@ func TestSkillCategory_FirstByName_NotFound(t *testing.T) {
 
 func TestSkillCategory_Create_SetsGameSystem(t *testing.T) {
 	setupLearningCostsTestDB(t)
+	gs := defaultGameSystem(t)
 
 	var src Source
 	require.NoError(t, src.FirstByCode("KOD"))
@@ -183,8 +193,8 @@ func TestSkillCategory_Create_SetsGameSystem(t *testing.T) {
 
 	require.NoError(t, err)
 	assert.NotZero(t, category.ID)
-	assert.Equal(t, "midgard", category.GameSystem)
-	assert.NotZero(t, category.GameSystemId)
+	assert.Equal(t, gs.Name, category.GameSystem)
+	assert.Equal(t, gs.ID, category.GameSystemId)
 }
 
 // =============================================================================
@@ -212,6 +222,7 @@ func TestSkillDifficulty_FirstByName_NotFound(t *testing.T) {
 
 func TestSkillDifficulty_Create_SetsGameSystem(t *testing.T) {
 	setupLearningCostsTestDB(t)
+	gs := defaultGameSystem(t)
 
 	difficulty := SkillDifficulty{
 		Name: "gs-diff",
@@ -221,8 +232,8 @@ func TestSkillDifficulty_Create_SetsGameSystem(t *testing.T) {
 
 	require.NoError(t, err)
 	assert.NotZero(t, difficulty.ID)
-	assert.Equal(t, "midgard", difficulty.GameSystem)
-	assert.NotZero(t, difficulty.GameSystemId)
+	assert.Equal(t, gs.Name, difficulty.GameSystem)
+	assert.Equal(t, gs.ID, difficulty.GameSystemId)
 }
 
 // =============================================================================
@@ -272,6 +283,7 @@ func TestSpellSchool_FirstByName_NotFound(t *testing.T) {
 
 func TestSpellSchool_Create_SetsGameSystem(t *testing.T) {
 	setupLearningCostsTestDB(t)
+	gs := defaultGameSystem(t)
 
 	var src Source
 	require.NoError(t, src.FirstByCode("KOD"))
@@ -285,8 +297,8 @@ func TestSpellSchool_Create_SetsGameSystem(t *testing.T) {
 
 	require.NoError(t, err)
 	assert.NotZero(t, school.ID)
-	assert.Equal(t, "midgard", school.GameSystem)
-	assert.NotZero(t, school.GameSystemId)
+	assert.Equal(t, gs.Name, school.GameSystem)
+	assert.Equal(t, gs.ID, school.GameSystemId)
 }
 
 // =============================================================================
@@ -527,6 +539,7 @@ func TestGetActiveSourceCodes_Success(t *testing.T) {
 func TestGetSourcesByGameSystem_Success(t *testing.T) {
 	setupLearningCostsTestDB(t)
 
+	gs := defaultGameSystem(t)
 	sources, err := GetSourcesByGameSystem("midgard")
 
 	assert.NoError(t, err)
@@ -534,7 +547,7 @@ func TestGetSourcesByGameSystem_Success(t *testing.T) {
 
 	// Verify that all returned sources are for the correct game system
 	for _, source := range sources {
-		assert.Equal(t, "midgard", source.GameSystem)
+		assert.Equal(t, gs.ID, source.GameSystemId)
 	}
 }
 
@@ -550,6 +563,7 @@ func TestGetSourcesByGameSystem_InvalidGameSystem(t *testing.T) {
 func TestGetSkillsByActiveSources_Success(t *testing.T) {
 	setupLearningCostsTestDB(t)
 
+	gs := defaultGameSystem(t)
 	// This function may have implementation issues, so we test but accept errors
 	skills, err := GetSkillsByActiveSources("midgard")
 
@@ -557,7 +571,7 @@ func TestGetSkillsByActiveSources_Success(t *testing.T) {
 	if err == nil {
 		// Verify that all returned skills are for the correct game system (if any returned)
 		for _, skill := range skills {
-			assert.Equal(t, "midgard", skill.GameSystem)
+			assert.Equal(t, gs.ID, skill.GameSystemId)
 		}
 	}
 	// If there's an error, that's acceptable as the function may have implementation issues
@@ -566,6 +580,7 @@ func TestGetSkillsByActiveSources_Success(t *testing.T) {
 func TestGetSpellsByActiveSources_Success(t *testing.T) {
 	setupLearningCostsTestDB(t)
 
+	gs := defaultGameSystem(t)
 	// This function may have implementation issues, so we test but accept errors
 	spells, err := GetSpellsByActiveSources("midgard")
 
@@ -573,7 +588,7 @@ func TestGetSpellsByActiveSources_Success(t *testing.T) {
 	if err == nil {
 		// Verify that all returned spells are for the correct game system (if any returned)
 		for _, spell := range spells {
-			assert.Equal(t, "midgard", spell.GameSystem)
+			assert.Equal(t, gs.ID, spell.GameSystemId)
 		}
 	}
 	// If there's an error, that's acceptable as the function may have implementation issues
@@ -582,6 +597,7 @@ func TestGetSpellsByActiveSources_Success(t *testing.T) {
 func TestGetCharacterClassesByActiveSources_Success(t *testing.T) {
 	setupLearningCostsTestDB(t)
 
+	gs := defaultGameSystem(t)
 	classes, err := GetCharacterClassesByActiveSources("midgard")
 
 	assert.NoError(t, err)
@@ -589,7 +605,7 @@ func TestGetCharacterClassesByActiveSources_Success(t *testing.T) {
 
 	// Verify that all returned classes are for the correct game system
 	for _, class := range classes {
-		assert.Equal(t, "midgard", class.GameSystem)
+		assert.Equal(t, gs.ID, class.GameSystemId)
 	}
 }
 
diff --git a/backend/transfer/importer_test.go b/backend/transfer/importer_test.go
index 7c1be9e..4f87fe1 100644
--- a/backend/transfer/importer_test.go
+++ b/backend/transfer/importer_test.go
@@ -102,7 +102,7 @@ func TestImportCharacterUpdatesIncompleteGSMData(t *testing.T) {
 	incompleteSkill := models.Skill{
 		ID:           1000,
 		Name:         "TestSkillIncomplete",
-		GameSystem:   "midgard",
+		GameSystemId: 1,
 		Beschreibung: "",
 		Category:     "",
 	}
@@ -122,7 +122,7 @@ func TestImportCharacterUpdatesIncompleteGSMData(t *testing.T) {
 		GSMSkills: []models.Skill{
 			{
 				Name:         "TestSkillIncomplete",
-				GameSystem:   "midgard",
+				GameSystemId: 1,
 				Beschreibung: "Complete description",
 				Category:     "Alltag",
 				Difficulty:   "normal",