Theme: Gravity

3D, but played in 2D (think New Super Mario Bros)
2 controls:
	With the arrow keys, change the direction of the gravity
	With the shift key, change how much the gravity is applied
1 objective: Bring the ball through all the rings

Music is proportional to the ball's velocity
Each level looks and sounds different

Have score be Sonic-like, there's a timer and it's converted into score, also add to score if ball collects certain stuff