In no particular order:
Gears 1 (set the standard for 3rd person shooters this gen, its formula has been imitated countless times)
MW1 (epic set pieces, highly cinematic. Medal of Honor, Uncharted, etc have copied this formula to a T. And you move to MP and Jeebus, its almost impossible to play ANY online game of any genre that has not incorporated some CoD element into it.)
Bioshock (no game this gen has come close to the immersion, tense nature of the gameplay, and environment than Bioshock imho. The biggest testament to the quality of the foundation that Bioshock laid out, is that the sequel is a far, far cry from the original, yet the sequel is still a 9 out of 10 type game imho)
Fallout 3 (just about as perfect a blend of RPG and shooter as you can get. Just an amazing expierience)
Red Dead Redemption (some of the writing and characters are kind of meh but overall the scope of the game and the amazing gameplay as well as the story overall made it one of the best of the gen imho)







