The Game View is very similar to the Scene View, giving a window into your game. In particular, the Game View shows which is the final result, what the player will see in your game. Also, the Game View can simulate different screen ratios. This allows you to control how your game will look on the different screens on which your game will run. Although this is a good preview, before a final release, you should still test on as many as real screens possible to ensure the best quality of your game. This is how it looks in Unity: