I'm working on something like that right now... it's more like a cross between Marble Madness / Super Monkey Ball / Gyroball / SpinDizzy / whatever else I'm forgetting. Dunno if cross is the right word, but it's SIMILAR to those games.
 
(This was actually the reason I requested LibMikMod be compiled, so I could have my cool techno-y music (that I composed! 

) playing. 

 )
I didn't want to let anyone know of this project, because talking too much about a WIP is the fastest way to kill it. 
 
If I finish up the win32 build enough to port it to the gp32 (as I intended to) and release a demo or something, I'll definately keep everyone updated. 
 
Well anyway, I also recommend Gyroball. Does Marble Madness work on the Mame emulator? If not, there are plenty of ports for other systems:
Genesis/Megadrive (Ok)
Gameboy (not very good)
Gameboy Color (really bad)
NES (My favorite! I recommend this one)
c64 (well, if you want to complete the collection... 

)
ZX Spectrum (I haven't actually played this one, but there's a level editor for it)
It's surprising when you think about it... you know, how much fun it is to roll a marble around in a video game. 
