1. Mass Effect 3
I'm one of those people that doesn't think the ending of the game was a crime against humanity, and even if I was, no ending could have diminished the hours upon hours of enjoyment Mass Effect 3 delivered.
2. Gotham City Impostors
There aren't many Xbox Live Arcade titles that have given me more value than Gotham City Impostors. Addicting gameplay with a steady flow of free content. Sure, the game is loaded with microtransactions, but save for a few weapons, no actualy gameplay content is behind the pay wall. There aren't many games so far in 2012 that I've spent more time with.
3. The Secret World
I've been playing a lot of MMOs the past few years, and I've enjoyed a few of them (SWTOR, for instance), but The Secret World is the first one that really feels like it's trying to break the mold and do something truly different. It will absolutely go free-to-play, the hooks are pretty much already there, but we're entering a world where free-to-play MMOs can not survive, but also thrive.
I don't think a game has ever captivated me based on sheer visual beauty more than Journey did. A shining example of games as art, the events of the game coupled with the unique co-op system forces the player to develop their own interpretation of what they're seeing unfold on screen, invoking emotional resonance without the need of slow-motion explosions, dramatic voice acting, or a Hans Zimmer soundtrack.
5. The Walking Dead
Even though the first six months of 2012 only saw two of the game's five total episodes, they were two REALLY GOOD episodes and I'm excited for the third episode hopefully arriving soon. I was wary of Telltale taking on another licensed franchise after Jurassic Park failed to really "wow" me, but those doubt have been assuaged.
6. Diablo III
I debated putting this on the list, if only because I rage-quit the game and uninstalled after hitting Act 2 of Inferno and realizing that I'd spend more time shopping for deals on the auction house and farming for gold than I did playing through the first three difficulties combined. I'm sure some people enjoy that, but it's not for me. Still, I enjoyed the majority of my time with it, even though I'll likely never play it again.