In no particular order:

Borderlands 2

Dust an Elysian Tale

Mass Effect 3

Double Dragon Neon

XCOM Enemy Unknown

Saints Row the Third - My 2011 Game of 2012

Binary Domain

Rhythm Heaven Fever

My last two picks were not released this year but I spent alot of time on:

Killing Floor

League of Legends

So having just finished the demo I'd like to share my thoughts on it. I'm going to add to this as I try it out further.

So first off the game's look and feel:

For the look it felt a lot like looking at WOW or a cartoony Dragon Age. But it was charming to see exaggerated proportions and really gave everything a good lively feel. The character movement felt a bit slippery at first but by the end of the demo it was already feeling pretty cozy for me. Furthermore, although slippery feeling, the controls were actually pretty tight for me.

Menus:

I have to say that the inventory system was so-so. Its a list that leads to another list, and then another list(going to equip able items). I would have like to see some multiple pages so that I wouldn't have to go 2-3 menus deep for weapons or armor. The Map was alright, the region map shows all the town and areas you've discovered clearly with icons for all the usual(quests, treasure, and shops).

Combat:

The combat as described is a bit more like Devil May Cry or God of War with combos. It felt pretty good, the roll dodge works like a roll dodge. Combos do have to be earned by leveling weapon skill types, so you only dump points in what you want to use. I really liked how bows were not forcing the player to abandon defense or force you to pick up arrows. The bow gives you 5-6 shots then arrows have to regenerate. A more DMC-like system was the fate system, similar to the devil transformation. The Fate system is show by the second meter that builds as you do damage to enemies. Upon activation it does damage to surrounding enemies and slows their movement while in effect. While activated it also increases player damage and allows them to perform finishers on enemies.

Class types:

In my first try of the demo, I played strictly as a Rogue. The daggers worked well and had familiar characteristics of speed and easy to combo. Rogues get gas cloud kind of spell that I found really useful.

-To be updated further-

Alright so after following Giant Bomb for a few months I just joined it today, took long enough for me to do so but hey whatever.
I'm still exploring the features of the site, quests are pretty interesting, and I'm looking forward to being a part of this.