Space Explorer!

Changes made to the tutorial version:

1. Three levels with different playing style 
2. Selection between two spacecrafts (a redisign of the original and a new tank-style ship)
3. A new enemy who acts as final boss 
4. Changes in the UI according to the levels

Note: The difficulty level of the game is set to be very easy, so it doesn't take a lot of time to test the three levels.