1. Mass Effect 2
Bioware pulled all the stops here. Improvements like meaningful (and fun) moral decisions, quality DLC, and vastly improved cover based shooter mechanics, resulted in a game that lived up to the initial hype this IP received when it launched in 2007.
The storyline was extremely compelling, and the meaningful relationships you forge throughout the game with your party lent the final chapter of the game an air of gravity.
Mass Effect 2 excelled in a year packed with other sequels because it didn't just improve upon its fore-bearer; it took an entire genre forward.
2. StarCraft II: Wings of Liberty
I've been playing Brood War competitively since 1998: I studied builds, streamed OSL/MSL games, surfed Teamliquid, got depressed by the match-fixing scandal; I did it all. It represented the pinnacle of RTS gaming to me and millions of diehards who never saw the ludicrousness in playing a game in 640x480 in 2010.
That Starcraft II met and surpassed my unreasonable expectations is a huge achievement in itself. Blizzard has hit the sweet spot; making it accessible to millions of new gamers, yet still maintaining a level of sophistication that will keep the community crazy about this game for years.
Walls of text have been written about the multiplayer, but it's often overlooked that the engrossing single-player campaign had a healthy amount of variety.
I hate to admit it, but after 12 years, it was all worth it.
3. Sid Meier's Civilization V
Civ V's changes (hex tile system, no more stacks of doom) are mind blowing and completely change the flow of the game, perhaps aligning it closer to what its developers intended so many years ago.
Gameplay is much more strategic in nature, demanding that players hone several aspects of leadership rather than barreling down the world map or quietly turtling to amass culture or science. The series' anachronistic charms are still in full effect though; nothing beats a B52 run over a country that's just discovered the wonders of the printing press.
I'm a bit ashamed to say I've logged less than 100 hours playing it, it's a title that demands your full attention.
4. Call of Duty: Black Ops
Dedicated servers returned triumphantly, once again making FPS gaming enjoyable for PC stalwarts. Treyarch's demonstrated a great willingness to continually tweak their product (which in my eyes is already the finest COD title to date), which may one day redeem them for their initially-unplayable PC launch.
Mad props have to go out to their multi-player designers for implementations such as the Flak Jacket perk; I notice that people are methodically pushing to cap objectives in CTF, DOM, DEM, HQ, which is a godsend.
The COD points and wager match modes are interesting, but aren't quite as genre-shaking as COD 4 was. In essence... you've played this game before. I'll still play it day in, day out but I just can't shake that niggling feeling that I wanted something more from this iteration.
5. Fallout: New Vegas
Its campaign is much more cohesive and tighter than Fallout 3's, and New Vegas is a very well-realized world that captures that awe and splendor that its real life counterpart inspires.
The inability to play for several factions was heavily criticized, but I felt this lent the game an air of realism in that my actions were meaningful and had consequences.
Well, until Gamebryo reared its ugly head and made someone walk in mid-air.
Darksiders clearly demonstrates that fresh ideas are not necessarily prerequisites for a quality game. Vigil creatively eschewed the current trend in game development (inserting 8, 16 bit mini-games) by updating classic gameplay for this era of consoles; that Panzer Dragoon sequence was a particular highlight! Its only drawback is the rather uninspired art direction, which came across as too generic. It's a shame though, I suspect it was the main reason why it was so easily dismissed earlier this year.
7. Football Manager 2011
FM gets a much-needed shot in the arm with the introduction of player interactions, more detailed negotiations, and agents that actively tout their clients to your club.
8. Napoleon: Total War
Napoleon is a smoother experience than Empire, and its single player campaign was a delight.
9. Super Meat Boy
A wonderful reminder of how games can be punishingly difficult yet enjoyable at the same time. Very nice throwback to the halcyon days of plaforming.
10. Just Cause 2
One of the most over-the-top and ridiculous games I've had the pleasure of playing.