Thanks almost single handedly to JohnCarmack and his support of OpenGL, a number of commercial games come out natively for Unix.

• Anything ID make (including Quake 1/2/3, Doom 1/2)
• Unreal Tournament and Unreal Tournament 2003

There was a company called Loki that ported many games to Linux. OliverJones knows a lot about them and will hopefully post a list. Unfortunately they've gone out of business, but they were responsible for the UT port, as well as:

Civilization: Call to Power, Myth II: Soulblighter, Railroad Tycoon II, Eric's Ultimate Solitaire, Heretic II, Heroes III, Heavy Gear II, SimCity? 3000, Soldier of Fortune, Sid Meier's Alpha Centauri, Descent3, MindRover?, Kohan: Immortal Sovereigns, Tribes 2, Rune, Heavy Metal: F.A.K.K.2, Postal Plus.

There's also a company called TransGaming who are working on a version of Wine called WineX? especially for gaming, which runs a whole heap of cool new games:

• Warcraft III
• Grand Theft Auto 3
• Civilisation III (Season for 3's, isn't it?)
• Black and White
• The Sims
• Everquest
• Jedi Knight II and other Quake 3 engine games

You can download the source code for WineX? under the GPL, but to download binaries from them you have to subscribe. Subscribing gives you the benefit of supporting them and a say in what games they work on supporting next, so it's highly recommended.

There are a number of cool GPL/free games for Linux:

• TuxRacer (which might not be free anymore, but it used to be)
• BzFlag
• XBill!

If programming games is more your thing, go have a look at the SDL (SimpleDirectMediaLayer).

Alternatively, go out and buy a console. Computers are for business. :)