Theme: Gravity

3D, but played in 2D (think New Super Mario Bros)
2 controls:
	With the mouse, change a slider to affect how much gravity is applied
	With the arrow keys, change the direction of the gravity
1 objective: Bring the ball to the opposite end of the level

Music should be proportional to either the gravity or the ball's speed, or maybe how close to the objective it is, probably not that
Each 2 levels should introduce a new mechanic like wind, moving platforms, bouncy walls...

Maybe an apple from a tree, to fall on Newton's head? Not that it'd have an apple's physics, though...
Have score be Sonic-like, there's a timer and it's converted into score, also add to score if ball collects certain stuff