...
System Shock / Bioshock series (of which I played only Bioshock 2, but heard good things about earlier games)[/i]
There is only System Shock (best games ever) and Bio Shock sucked hard.
Ok to be fair, Bio Shock 1 is similar to System Shock 2, but without of some important features, ingame atmosphere and most important without SHodan.
My current favorites are
Dead Space
Dragon Age
Mass Effect 2 (yeah ME 1 was nice, but fights were too slow and the UI was cruel).
Street Fighter 4 (ahh, i hate Ryu and Ken, and Guile, and Sagat and Blanka and ... )
World of Goo
Drakensang: River of Time (i like the story more than from the original Drakensang. Here you are not the chosen one to save the world, but a simple person at the wrong place to the wrong time)
and some classics
Mario Kart (Haha, power slide and a red turtle shell in your face)
Flood (yeah, survive 42 levels and get overrun by a car
)
Prince of Persia (the original 2D one)
Simon the Sorcerer 1+2
Gobliiins, Gobliins 2, Goblins 3 and Woodroof - The Schnibble of Azimuth