1. Metal Gear Solid 4
What more can be said? A fitting end to perhaps the most epic... err, opus(?)... ever presented in this medium.
2. Fallout 3
I've loved Bethesda's style of large-scale RPG since Morrowind, and this was a superb melding of that with one of the most interesting and well-crafted settings/narratives/worlds in games. Playing the originals now, years after the fact, they are like perfect blueprints for everything Bethesda accomplished with this.
3. Dead Space
Amazingly atmospheric and cohesive. Other than MGS4, this is probably the most cohesive, focused experience I had this year. Makes me so hot for a System Shock 2 remake by the same team.
4. Bionic Commando Rearmed
Having never played Bionic Commando before, this was almost like a revelation for me. Such awesome, incredibly tight and unique gameplay, mixed with extremely good electro-oldschool remixes on the soundtrack and great visuals.
5. Burnout Paradise
Just some of the most enjoyable, balls-out racing gameplay in years.
6. Left 4 Dead
I've had countless great experiences with a group of friends in this game, and for that alone it deserves a spot on the list.
7. Mirror's Edge
I finished the game on a weekend, and though it has many design choices that I take issue with, the core gameplay of the movement often provided some of the most exhilirating moments found this year.
8. Braid
Joins a small circle of games that I feel at least challenges the question of games as art.
9. Grand Theft Auto IV
I've played it through twice, one of which was an incredibly bug-laden play through on the PS3, which I think should speak enough to the quality of the single player experience. It's still janky, but at its core the experience is worth it.
10. Wipeout HD
Superb gameplay, superb audio and visual style. Wipeout is for real again.
MGS4 and Fallout 3 are essentially a tie for me, but I'm giving it to MGS4 just because it's Snake's last hurrah, and damn it, Snake deserves it. Yakuza 2 would probably be right there with MGS4 and Fallout for me, but I still haven't dug into my copy. Will probably get to that in a week or two. And Rez HD is one of my all time favs, too, but as said before that isn't really fair to count.
Disappointments of the year: LittleBigPlanet, Prince of Persia, Mega Man 9. LBP I still respect immensely for its ambition and design, and it's a wonderful looking (and sounding; very eclectic soundtrack) game, but the core gameplay just didn't hold my interest. I've detailed my disappointment with PoP in another thread, and MM9 is probably a respectable game, but the difficulty just seems stupid and cheap to the point where I just don't care enough to keep pushing forward. I didn't care for World of Goo at all, either.
Honorable Mentions: Red Alert 3, Crysis Warhead, God of War: CoO, Lost Winds, GeoWars2. All very good, but offered nothing truly memorable/outstanding.

