As a challenge I took the step to 3d and came up with a simple game, steer round the screen (arrows,x,z) and bash into the crystals:
I think it looks rather nice, hit all ten crystals and get your best time. If you want, please use, adapt and impove; but keep me informed. It's called marbles because I lost them in the 3d geometry. Is this a UK only phrase?!?