Okay... where should I start?
Fable 2? While I havent played Fable 1, just glancing at it lets me know it is just the kind of game I like... and now I am set to borrow and play the first before the second comes out.
Dead Space. While normally I dont like horror games, this one stands out. It has a unique combat system, very intense story (as in the makers made sure to not make story an excuse, but instead a major driving point of the game), and a very cool setting. A definite must get.
Fallout 3. For those of you who dont know, Fallout 1 and 2 pretty much were the beginning of the future of video game freedom. They were the first to not only have a non-linear game play (instead of being herded from one area to another, you had a huge map in which you could explore as you wished), but also were one of the first to cater to the mature gaming crowd. It is not a kids game. Unfortunately, the company that made it... fell into the abyss of bickering and red tape. it disappeared... but not before leaving its mark. The games most influenced by it I think are the Elder Scrolls... which take its idea of freedom to the extreme.
Now, Bethesda, the creator of the Elder Scrolls, have purchased the rights to Fallout and resurrected the post apocalyptic future from the past... And they have been making the game for FOUR YEARS. Now only a couple of months from release... it has the potential to be one of the greatest games of all time.