diff --git a/src/GameServer.spec.ts b/src/GameServer.spec.ts
index 20f7f0a..7e98dc5 100644
--- a/src/GameServer.spec.ts
+++ b/src/GameServer.spec.ts
@@ -105,15 +105,12 @@
     const mapID = "lvl1";
     describe("When a user starts an existing valid level", function(){
         const games = createGameServer();
-        const position = games.startGame(userID, mapID);
-
-        it("then the start position must exist", function(){
-            expect(position).to.be.not.null;
-        });
+        games.startGame(userID, mapID);
 
         it("then the start position must be remembered for the user", function(){
             const current = games.currentPosition(userID);
-            expect(current.id).to.equal(position.id);
+            expect(current, "Position object is null.").to.be.not.null;
+            expect(current.id, "Id of the tile is null.").to.be.not.null;
         });
     });
 
@@ -158,13 +155,59 @@
     });
 });
 
+describe("Scenario: Ending the game", function(){
+    const userID = "UserID";
+    const mapID = "lvl1";
+
+    describe("Given a started game.", function(){
+        const games = createGameServer();
+        games.startGame(userID, mapID);
+
+        describe("When the games is ended", function(){
+            const notBreakingFunction = () => {
+                games.endGame(userID);
+            };
+            it("then no exeption should be thrown.", function(){
+                expect(notBreakingFunction).to.not.throw;
+            });
+        });
+    });
+
+    describe("Given a started and ended game.", function(){
+        const games = createGameServer();
+        games.startGame(userID, mapID);
+        games.endGame(userID);
+
+        describe("When the current position is queried", function(){
+            const position = games.currentPosition(userID);
+
+            it("then current position should be null.", function(){
+                expect(position).to.be.null;
+            });
+        });
+    });
+
+    describe("Given no started game.", function(){
+        const games = createGameServer();
+
+        describe("When the game is ended", function(){
+            const result = games.endGame(userID);
+
+            it("then it should return true.", function(){
+                expect(result).to.equal(true);
+            });
+        });
+    });
+});
+
 describe("Scenario: Navigating in ongoing game", function(){
     const userID = "UserID";
     const mapID = "lvl1";
 
     describe("When player navigates in existing direction", function(){
         const games = createGameServer();
-        const startPosition = games.startGame(userID, mapID);
+        games.startGame(userID, mapID);
+        const startPosition = games.currentPosition(userID);
         const naviagtionDirection = startPosition.paths[0];
         const nextPosition = games.navigate(userID, naviagtionDirection);
         it("then the new position has to have a different id", function(){

diff --git a/src/GameServer.spec.ts b/src/GameServer.spec.ts
index 20f7f0a..7e98dc5 100644
--- a/src/GameServer.spec.ts
+++ b/src/GameServer.spec.ts
@@ -105,15 +105,12 @@
     const mapID = "lvl1";
     describe("When a user starts an existing valid level", function(){
         const games = createGameServer();
-        const position = games.startGame(userID, mapID);
-
-        it("then the start position must exist", function(){
-            expect(position).to.be.not.null;
-        });
+        games.startGame(userID, mapID);
 
         it("then the start position must be remembered for the user", function(){
             const current = games.currentPosition(userID);
-            expect(current.id).to.equal(position.id);
+            expect(current, "Position object is null.").to.be.not.null;
+            expect(current.id, "Id of the tile is null.").to.be.not.null;
         });
     });
 
@@ -158,13 +155,59 @@
     });
 });
 
+describe("Scenario: Ending the game", function(){
+    const userID = "UserID";
+    const mapID = "lvl1";
+
+    describe("Given a started game.", function(){
+        const games = createGameServer();
+        games.startGame(userID, mapID);
+
+        describe("When the games is ended", function(){
+            const notBreakingFunction = () => {
+                games.endGame(userID);
+            };
+            it("then no exeption should be thrown.", function(){
+                expect(notBreakingFunction).to.not.throw;
+            });
+        });
+    });
+
+    describe("Given a started and ended game.", function(){
+        const games = createGameServer();
+        games.startGame(userID, mapID);
+        games.endGame(userID);
+
+        describe("When the current position is queried", function(){
+            const position = games.currentPosition(userID);
+
+            it("then current position should be null.", function(){
+                expect(position).to.be.null;
+            });
+        });
+    });
+
+    describe("Given no started game.", function(){
+        const games = createGameServer();
+
+        describe("When the game is ended", function(){
+            const result = games.endGame(userID);
+
+            it("then it should return true.", function(){
+                expect(result).to.equal(true);
+            });
+        });
+    });
+});
+
 describe("Scenario: Navigating in ongoing game", function(){
     const userID = "UserID";
     const mapID = "lvl1";
 
     describe("When player navigates in existing direction", function(){
         const games = createGameServer();
-        const startPosition = games.startGame(userID, mapID);
+        games.startGame(userID, mapID);
+        const startPosition = games.currentPosition(userID);
         const naviagtionDirection = startPosition.paths[0];
         const nextPosition = games.navigate(userID, naviagtionDirection);
         it("then the new position has to have a different id", function(){
diff --git a/src/GameServer.ts b/src/GameServer.ts
index 4d59d2f..03753ad 100644
--- a/src/GameServer.ts
+++ b/src/GameServer.ts
@@ -53,7 +53,7 @@
         }
     }
 
-    public startGame(userID: string, mapID: string): MazeTile
+    public startGame(userID: string, mapID: string): boolean
     {
         this.userIdGuard(userID);
         const map = this.mapList.find(m => m.id === mapID);
@@ -74,7 +74,17 @@
             state.tileID = start.id;
         }
 
-        return start;
+        return true;
+    }
+
+    public endGame(userID: string): boolean
+    {
+        const stateIndex = this.states.findIndex(s => s.userID === userID);
+        if(stateIndex !== -1)
+        {
+            this.states.splice(stateIndex, 1);
+        }
+        return true;
     }
 
     public navigate(userID: string, direction:Direction): MazeTile

diff --git a/src/GameServer.spec.ts b/src/GameServer.spec.ts
index 20f7f0a..7e98dc5 100644
--- a/src/GameServer.spec.ts
+++ b/src/GameServer.spec.ts
@@ -105,15 +105,12 @@
     const mapID = "lvl1";
     describe("When a user starts an existing valid level", function(){
         const games = createGameServer();
-        const position = games.startGame(userID, mapID);
-
-        it("then the start position must exist", function(){
-            expect(position).to.be.not.null;
-        });
+        games.startGame(userID, mapID);
 
         it("then the start position must be remembered for the user", function(){
             const current = games.currentPosition(userID);
-            expect(current.id).to.equal(position.id);
+            expect(current, "Position object is null.").to.be.not.null;
+            expect(current.id, "Id of the tile is null.").to.be.not.null;
         });
     });
 
@@ -158,13 +155,59 @@
     });
 });
 
+describe("Scenario: Ending the game", function(){
+    const userID = "UserID";
+    const mapID = "lvl1";
+
+    describe("Given a started game.", function(){
+        const games = createGameServer();
+        games.startGame(userID, mapID);
+
+        describe("When the games is ended", function(){
+            const notBreakingFunction = () => {
+                games.endGame(userID);
+            };
+            it("then no exeption should be thrown.", function(){
+                expect(notBreakingFunction).to.not.throw;
+            });
+        });
+    });
+
+    describe("Given a started and ended game.", function(){
+        const games = createGameServer();
+        games.startGame(userID, mapID);
+        games.endGame(userID);
+
+        describe("When the current position is queried", function(){
+            const position = games.currentPosition(userID);
+
+            it("then current position should be null.", function(){
+                expect(position).to.be.null;
+            });
+        });
+    });
+
+    describe("Given no started game.", function(){
+        const games = createGameServer();
+
+        describe("When the game is ended", function(){
+            const result = games.endGame(userID);
+
+            it("then it should return true.", function(){
+                expect(result).to.equal(true);
+            });
+        });
+    });
+});
+
 describe("Scenario: Navigating in ongoing game", function(){
     const userID = "UserID";
     const mapID = "lvl1";
 
     describe("When player navigates in existing direction", function(){
         const games = createGameServer();
-        const startPosition = games.startGame(userID, mapID);
+        games.startGame(userID, mapID);
+        const startPosition = games.currentPosition(userID);
         const naviagtionDirection = startPosition.paths[0];
         const nextPosition = games.navigate(userID, naviagtionDirection);
         it("then the new position has to have a different id", function(){
diff --git a/src/GameServer.ts b/src/GameServer.ts
index 4d59d2f..03753ad 100644
--- a/src/GameServer.ts
+++ b/src/GameServer.ts
@@ -53,7 +53,7 @@
         }
     }
 
-    public startGame(userID: string, mapID: string): MazeTile
+    public startGame(userID: string, mapID: string): boolean
     {
         this.userIdGuard(userID);
         const map = this.mapList.find(m => m.id === mapID);
@@ -74,7 +74,17 @@
             state.tileID = start.id;
         }
 
-        return start;
+        return true;
+    }
+
+    public endGame(userID: string): boolean
+    {
+        const stateIndex = this.states.findIndex(s => s.userID === userID);
+        if(stateIndex !== -1)
+        {
+            this.states.splice(stateIndex, 1);
+        }
+        return true;
     }
 
     public navigate(userID: string, direction:Direction): MazeTile
diff --git a/src/LabyrinthMiddleware.ts b/src/LabyrinthMiddleware.ts
index fb7b857..db93e45 100644
--- a/src/LabyrinthMiddleware.ts
+++ b/src/LabyrinthMiddleware.ts
@@ -22,7 +22,10 @@
 
     type Mutation {
         "Start a new game"
-        startGame(userID: String!, mapID: String!): MazeTileQL
+        startGame(userID: String!, mapID: String!): Boolean!
+
+        "Cancels a currently running game"
+        endGame(userID: String!): Boolean!
     }
 
     type Query {
@@ -61,8 +64,9 @@
 {
     return {
         currentPostition: ({userID}) => new MazeTileQL(games.currentPosition(userID)),
+        endGame: ({userID}) => games.endGame(userID),
         listMaps: () => games.listMaps(),
-        startGame: ({userID, mapID}) => new MazeTileQL(games.startGame(userID, mapID)),
+        startGame: ({userID, mapID}) => games.startGame(userID, mapID),
     };
 }