I am a FPS fan but i can try my hands at anything which is decent.
Already done are:
Batman AA and Modern Warfare 2
Splinter Cell: Chaos Theory was the last game I really enjoyed.
If you loved playing Batman the ninja way, you will find this even better.
Try dragon age origins..
GOTY for many sites..
DAO is just awesome. Give it a shot.
Call of Juarez:Bound in Blood
Brothers in Arms Hells Highway
Fallout 3
Bioshock
Dragon Age Origins
Crysis
Crysis Warhead
Mass Effect
HAWX
Prototype
Borderlands
Grand Theft Auto 4
Cryostasis
Lost Planet
Time Shift
Quake 4
Assassins Creed
Wolfienstein
Fear 1/2
FarCry 2
StreetFighter 4:clap:
Spore…
for starters:
Dragon Age Origins
Risen
Divinity 2
Drakensang
Mass effect
Warhammer Dawn of War II
Prototype
I would recommend
Mass Effect
Thief Deadly Shadows
Batman Arkham Asylum
Modern Warfare
Farcry
Borderlands - awesome fun
Dragon Age Origins - I hated it, but my brother is absolutely crazy about it and also a LOT of other people 
older games
FarCry 2 - most people hate it, but I like it
BioShock - awesome game
Fallout 3 - again awesome game
lots of other games released last year which I havent tried yet: L4D2, Red Faction Guerilla, Wolfenstein, Saboteur etc…
Hello kitty island adventure
Which platform?
GTA IV.
halo 1 and halo 2.i liked halo 2 the most.
and all those mentioned by other members.
try CoMmand & CoNquEr GENERALS..!!
I USEd To Play lOnG Bak..!!
I say, try The Saboteur. It’s great.
Try Dirt 2
If playing on LAN then enjoy the all time great game “Counter Strike”. It rocks
saboteur has performance issues…lags a lot…n not dat gud too…
borderlands is really gud