i am playing at the moment crysis 2 and dead space 1 ....
dead space 1 awesome game for me though crysis 2 is also nice
dragon age 1 and 2 are awesome.
now i am playing crysis 2..
deadspace 2 is also very good.
3rd and you can play these games with all the side quests for weeks
You must play Mirror's Edge it is one of the best games I have ever played
Dragon Age 1 and 2 are great too
and of course Mass Effect 1 and 2 you musn't miss them
I also suggest Portal 1 and 2.