A (slightly) modernized port of Quake II to D3D9.
You need SM3 or better hardware to run this - if you don't have it, then don't even bother.
It should work on Windows Vista, 7 or 8; it may also work on XP but I haven't tested.
Known bugs include:
Some mods may not work. This is unfortunately due to the nature of Quake II's game DLLs; sometimes a recompile of the game DLL is all that's needed. In any event, ensure that the game DLL is compatible with the last release of Quake II first (3.20).
In some maps some surfaces may not get added to the PVS. In the main game this is restricted to one surface in the Inner Hangar map.