Don't forget CalcNet has an inherent limit of roughly 105 calcs anyways.
The Only thing that needs to stay the same between Calc and PC versions of anything is communication methods. If the PC version has Full 3D but the Calc version is isometric, so be it, but they have the same location identifiers. granted, physics wouldn't be wondrous.

@Ashbad he meant a web browser
What about having these for two versions: a Calc version through gCn or the like, and a Java version in a browser, that is only different in screen resolution? Maybe sound too, but hey, let's keep it nice, while reasonable.
@Juju, interesting concept! Sounds like a 1player game, but still, possibly expandable.
@Compy about svn, you can just install the original svn for linux. It was made for it after all

just apt-get install (or similar for others) subversion
What about just using sourceforge for Svn/git hosting?
EDIT: BTW, a cross-platform language.....BBC BASIC already has ARM ports (Brandy), and an 84+version by benryyves to boot! It's also really fast! And it's easy, since it's a real BASIC, not BASIC-wrapped asm like axe (makes axe more powerful, but harder) so the only thing to learn is the new syntax! (It's like real BASIC, with print, not disp, GOTO 10 is valid, etc.)