Warhammer 40,000: Space Marine is this year's most overlooked shooter. It isn't just good, it's fucking fantastic(it beats the high holy hell out of Gears of War 3), and the fluid combat, terrific multiplayer, and various, exciting campaign are all worthy of note and praise. Oh well. I hear tell it sold decently, so maybe we'll get another. I'd like that.
This is a bit of a stretch considering that it clean-swept the "best fighting game" category at every awards show ever and sold like hotcakes, but I don't think people fully appreciate just how goddamn good Mortal Kombat really is. Skillful fighting mechanics, solid balance, a dedicated dev team at the community's beck and call, and a hi-fucking-larious story mode make this the best fighting game to be released since Street Fighter IV turned fighting games into casually-oriented Xbox LIVE vehicles and ruined the genre for everybody who ever held it dear.
On that note, let's talk about The King of Fighters XIII. This is as old-school as it gets: a sprite-based fighting game with strict execution, a multitude of useful mechanics, and no fucking stupid comeback system that rewards the losing player(seriously, fuck Street Fighter IV). It's unlikely to be a big hit since it lacks the accessibility that the modern gamer craves, but it's what a fighting game should be: a skill-based measure of technical prowess and mental gymnastics. I applaud SNK for having the balls to defy the modern trend of fighting games as manufactured e-sports for the Xbox LIVE crowd and remember what the genre is meant to be about.
Duke Nukem Forever is a thoroughly average game. It is not the worst game of 2011(that would be either Catherine or Brink). It is nowhere near the worst game of all time. It's just average, and no amount of pretentious scoffing at it will change that, no matter what your little e-friends on your My Little Pony GeoCities fansite tell you. Deal with it.
Infamous 2 is much, much better than several of the big contenders for top honors at this year's awards shows(hello, Skyward Sword, why are you sitting next to Skyrim? You should be at the back of the bus). Excellent writing, intuitive controls, a decent difficulty curve, and versatile combat make this one of the best sandbox games ever made. This is the killer app that the PS3 needs. Uncharted 3 is not.
While all of the above games are valiant underdogs deserving of much more praise than they received, the single most criminally underrated game of 2011, and indeed one of the most underrated games I've ever played, is the unrivaled powerhouse in interactive storytelling that is Bastion. Not only is Bastion the best game of 2011, it's the best Xbox LIVE Marketplace title ever, one of the best action-RPGs ever, and proof positive that video games are capable of telling stories in a way that no other medium can. It's rare that such a masterpiece rolls along, and the fact that people were too busy slurping up Shigeru Miyamoto's latest turd to notice it is just fucking sad.