Okay, R6 Vegas2 is a decent tactical shooter. Assassins Creed 2 is well worth playing, especially if that version has the extra content as well.
Ok I've widened the list I gave earlier as well as giving you an idea of what each game is about.
Skyrim (especially with all the DLC) - Open World Fantasy Role Playing Game
Fallout 3 (especially with all the DLC) - Post Apocalyptic Open World Role Playing Game
Fallout New Vegas (especially with all the DLC) - Post Apocalyptic Open World Role Playing Game
Dead space 1 & 2 - Science Fiction Survival Horror
Assassins Creed Black Flag - Assassins and pirates. Plunder the seas with your own ship along side legends like Blackbeard
Xcom: Enemy Unknown/Within - Turn based strategy against alien invaders. Cryssalids are utter bastards.
Red Dead Redemption - Open World Wild West Role Playing Game. The zombie DLC was amusing as well.
GTA V - Open World modern criminal Role Playing Game. The online map can be both irritating as hell and great fun at the same time.
Batman Arkham Asylum - You are playing Batman, what more needs to be said
Fable 1, 2 & 3 - Quirky Fantasy Role Playing Games
Deus Ex Human Revolution - One of the all time greats. Distopian future shock Role Playing Game
Forza Motorsport 4 - Tinker with and drive some of the most desirable Fast cars on the planet
Borderlands 2 - If your three favorite things on the entire planet are guns, toilet humor, and min/maxing RPG stats, then Borderlands 2 is a dream come true
Portal - A puzzle game that will drive you around the bend. Actually get the Orange box and you get Portal, Half Life 1 and 2 and as well as a bunch of other games.
Bioshock - Strange twisted survival horror shooter
Possibly Destiny as well, depending on what kind of offer you get for the extra content.