I play games for many reasons.
But often very often its to explore the limits of my hardware. For the average home user games are hands down the most difficult applications for our computers to run.
They are in effect a demonstration of technology.
For that reason I love Crisis warhead 64. The eye candy and sounds are just awesome.
For GREAT on-line multi player running and gunning I love Unreal tournament 3.
Fantastic action, active on-line community, mature bug free status, lots of mods,
fantastic servers world wide.
For late night creepyness and Fear 2 is excellent as is Left for Dead 1 and 2. Also GREAT for eye candy.
Currently my most dissapointing game is Mirrors Edge... In my opinion the environment looks like crap and the game play world/concept of hot Asian chicks running around and jumping on stuff is not enough of a draw. I got it to show case Nvidias Physx. Major YAWN!