1. Batman Arkham City 2. Skyrim 3. Fallout 3 4. Ultimate Marvel vs Capcom 3 5. Super Street Fighter IV AE 6. Pokémon White/Black and Pokémon White/Black 2 7. Kingdom Hearts Birth by Sleep 8. Pokémon Platinum 9. Street Fighter X Tekken 10. Kingdoms of Amalur: Reckoning
Honorable mentions include Tekken Tag Tournament 2, the whole Mass Effect trilogy, Borderlands 2, they're honorable mentions simply because I haven't gotten a chance to play them but I'm sure they would place in my list. Also God of War 3 but I have played it.
Skullgirls Left 4 Dead Mario Kart 7 Ninja Gaiden II Saints Row the Third Smash Bros Brawl Earth Defense Force: 2017 (Awesome for Couch Co-Op) Portal 2 Way of the Samurai 3 DBZ: Budokai HD Collection (Budokai 3 is one of my favorite fighters, and Budokai 1 is very nostalgic. Don't like the re-done half-assed soundtracks though.)
Out of this list, I think Skullgirls is my favorite.
Tales of Vesperia Left 4 Dead/2 Super Mario Galaxy 2 Ninja Gaiden Sigma 2 Super Smash Bros. Brawl Lufia DS Curse of the Sinistrals Kingdom Hearts Birth By Sleep Metroid Other M Pokemon Soul Silver Legend of Zelda Twilight Princess