Bigbigbig majority of new games out there are playable in Win2k... if it's the "next hot thing" in gaming, it will support Win2k since most new games use either DirectX 7/8 or OpenGL... both of which Win2k supports. Any games that don't work well (Pools of Radiance *AHEM*) can pretty much be assumed not be of a decent software quality.
In fact, I can't remember an award-winning game of this year that didn't support win2k... Ghost Recon, Medal of Honor, Return to Castle Wolfenstein, Civ3, Wizardry8, Diablo 2:LOD, EverCrack, etcetcetc. all of them run and run just as fast (if not sometimes faster) than in 98/ME.