I might miss a few, since I'm doing this off the top of my head, but I'll give it a shot. I play on PC, 3DS, and PS3 so my choices are limited to those platforms.
1. Metal Gear Rising - I'm a fan of Metal Gear Solid, and a fan of Platinum's work - how could I not be hyped by this one? The glimpses we've seen are promising, and I'm very happy to hear that it'll be running at 60FPS, just as any action game should. This is the big one for me.
2. Grand Theft Auto V - As crazy as it may sound, I didn't have much love for this series until GTAIV. I loved the detailed city, the awesome physics and even the realistic car handling. There are very few studios, if any at all, that can produce a game that rivals the scale and production values of a Rockstar North game. I just hope there will be a PC port!
3. Risen 2 - Risen 1 was a quality open-world RPG thanks to it's hand crafted environments and the lack of level scaling that drags down Bethesda's games. It had a few issues, like the frustrating combat, but it could be among the best RPG's of the past several years with a few key improvements. The most appealing aspect of R2 is the pirate theme, I mean, who wouldn't get excited by the idea of a swashbuckling RPG?
4. Twisted Metal - It doesn't seem to be generating as much hype as some of Sony's other high profile IP's, but I'm pretty excited. It's got Jaffe at the helm, the footage I've seen looks very good, and I'm just a fan of violent vehicular combat in general. The recent news of a M rating seals the deal for me.
5. Mass Effect 3 - This should be higher, since I'm quite fond of the first two games, but nuBioware have done their best to kill my hype. Judging from the footage we've seen, they seem intent on making it an INTENSE, VISCERAL, ACTION-PACKED CINEMATIC EXPERIENCE, which is the last thing I want from the series, but it's possible that they haven't shown the good parts yet. It's still a must-play for me, but my expectations are tempered.
6. Far Cry 3 - This could go either way, some of the stuff shown in the reveal is troubling (particularly the CoD-style number pop ups), but it certainly has potential. FC2 may have had some serious issues, but it was a very ambitious game and if Ubi can build from that, it could be something special. It'll probably fall of this list if there is no PC version, though.
7. Sly Cooper 4 - What we've seen so far isn't exactly promising, and while Sanzaru did a great job with the HD collection, I wish that Sucker Punch were on board. That being said, I'm a fan of the series and platformers in general, so it's a sure thing for me unless it turns out really bad.
8. Resident Evil: Revelations - Early reviews are mixed, but as long as it has some good scares and competent controls, it should be a worthwhile experience.
The rest:
Devil May Cry HD collection , Paper Mario 3DS, Max Payne 3, and The Last of Us.
S.T.A.L.K.E.R. 2 and Dead State (zombie RPG created by some ex-Troika members) would be at the top of my list, but who knows if they'll come out in 2012, or at all for that matter.