Infinite Space: Funky space RPG game heavily influenced by Macros and Gundam and such, and theoretically influences by Arthur C Clarke.
Dragon Quest 9: I didn't like the story so much, but the mechanics were good, and the tagging stuff was interesting (at least if you take the time to go to meet-ups and such =)
Civilization V: Despite the various controversies about bugs and style decisions, it still sucked me in for a good long while :)
Beat Hazard: I'm not usually into twin-stick shooter type games, but the ability to have it synch to whatever music i wanted in a psychedelic explosion just blew me away.
Recettear: An Item Shop's Tale: It's a game where you run an item shop, selling items to townspeople and adventurers. You also have the option of going on adventures in the dungeon yourself if you
want to break things up. It's cute and fun _and_ a new and unusual game idea.
Rock Band 3: I haven't had much time to play it yet, but it is awesome, especially since this is my first foray into Rock Band world.
Honorable mention: Final Fantasy 13. It's a pretty good game in its own right, but as the latest edition in one of my favorite series i had a couple problems with it. Also didn't help that my PS3 got the Yellow Light of Death before i was "done" with it.
Other good games that haven't quite sucked me in yet: Super Meat Boy, Swords and Soldiers HD, BIT.TRIP.BEAT, Braid, Eufloria, Galcon Fusion, Gratuitous Space Battles, Shatter
Games sitting in my pile of shame that i really need to get around to: Mario Galaxy 2, Kirby Epic Yarn, Enslaved, 3D Dot Heroes, Infamous, Metroid Other M, Final Fantasy 4 Heroes of Light, Disgaea 3, Nostalgia, and possibly a few others i'm forgetting. Plus a ton of other Steam games that i bought during the big December sales.