Matter of fact:
I run, UT, UT2003, UT2004, NWN, many SCUMM-engined games, Wesnoth, Quake2 is available for free now.
Winex doesn't "emulate", based on Wine (Wine Is Not an Emulator)
They provide the APIs and other such things. P;us they *CAN* use Windows DLLs.
I am currently running: SIMs, a coupla Star treks, a few other games (Fallout 1/2), Diablo 1/2, Alien vs Predator. System Shock 2. Yeah I have many old games. Many work, some don't
Lotsa other things are currently said to work, that I don't have.
Half Life 2 seems to be using an engine that *IS* possible to have on Linux... just the developer of that engine, has been threatened... err talked to, by a certain other company.