Counting Colors

All of my code are inside CountingColors /CountingColors /src /com /lemuelcastro folder
The problem po kasi is the GameScreen per se is not an activity (so I cant really use retainInstance) but a SurfaceView po so whenever the  home button is pressed the instance of GameScreen po is destroyed. By Using a singleton i can keep the GameScreen alive, but since once intance of a class lang po ang pwede I needed to explicitly set it to null for every activity call (especially in Main Menu and GameOver Class) since a new game must be produced (with a Random set of Tiles) po.