protected override void Update(GameTime gameTime)
 {
     currentKb = Keyboard.GetState();
     if (level.gameState.state==State.over)
     {
         if (currentKb.IsKeyDown(Keys.Enter) && previousKb.IsKeyUp(Keys.Enter))
         {
             level.gameState.state = State.menu;
             level = new Level(Services);
         }
     }
     if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
         this.Exit();
     base.Update(gameTime);
     level.Update(gameTime);
     previousKb = currentKb;
 }
 protected override void Initialize()
 {
     IsMouseVisible = true;
     level = new Level(Services);
     base.Initialize();
 }