Diablo 3
Diablo was great, and Diablo 2 was even better, and Dark Stone was an awesome 3d replacement for a while. Then, I got into Torchlight, and I am looking at Torchlight 2 as my coop title in 2012, but Diablo 3 should also be around the corner, and it, too, sports coop features. I will be grabbing Diablo 3 eventually. Diablo 3 and Torchlight 2 are both on my list of games I simply must get. Torchlight 2 should be released this year, while Diablo 3 is scheduled for 2012.
Halo 4
We all thought Halo was a dying franchise, but it just keeps going! I started to lose interest when I played Halo ODST and Halo Wars, but Reach bought me back, and I really want Halo 4. Halo Anniversary also looks like a nice alternative.
Skyrim
This is technically a late 2011 release, but we will be getting in most of our play time in 2012. Skyrim is simply a time sink that we may keep playing for years, until the next Elder Scrolls game comes out.
Skyward Sword
The Legend of Zelda: Ocarina of Time stole countless hours of my life, and I simply loved The Minish Cap and Twilight Princess. Skyward Sword is the next step for this franchise, and I simply am a fan. It is too bad I missed out on Spirit Tracks and most of Phantom Hourglass, but each game is almost totally unrelated, anyway.
Syndicate
This game looks like Deus Ex: Human Revolution, has procedural AI, and offers online, 4-player coop. It simply looks like it could be the best coop option in 2012.
I was very much looking forward to Diablo 3 for the longest time until I saw a gameplay video not too long ago. It looked very nice, but at that moment I decided I wasn't sure I wanted to buy it when it came out. And when my friends and I watched the Xbox convention as Halo 4 was announced I knew right away I wasn't going to buy it. Simply because I don't trust 343 Studios with a whole franchise... yet.
On the other hand, Skyrim is a mere 2 weeks away and I couldn't be more excited. I have patiently waited for the next Elder Scrolls game and am ready to reap the sweet rewards of the wait. Skyward Sword also looked really neat; to my brother and I it looked like the gameplay of Twilight Princess met with the graphics of Windwaker. Needless to say, it looks like a very awesome combination. Though probably not a game I would get off the bat.
Killed by a troll on level 14.