Poker Night at the Inventory - Steam link
Perhaps surprisingly, Poker Night at the Inventory is worth buying simply because it's a good poker game. There aren't a lot of frills to the game, but the un-tampered-with simplicity is what makes it such a good choice. The AI seems slightly erratic at times, but some would argue that that's how poker should be played. (Or the AI is just trouncing me regardless... and I'm still on normal difficulty!) What Poker Night lacks in variety, it makes up for in its straightforward-ness. If you're looking for a good, cheap poker game that may surprise you with the occasional laugh, Poker Night at the Inventory is worth a go.
VVVVVV - Steam link - (demo available)
That was nearly a year ago now, and after multiple replays through the game, beating that passage is absolutely no problem at all for me. I've mastered the game to the point where I can beat it in about a half hour, and with a fraction of the deaths it took me before. Amazingly, this game has still not lost its appeal. Despite its simplicity when every room is well-practiced, I still come back this game to tackle a level in a speedrun. Earlier today, I loaded up the game just so I could listen to the music while wrapping Christmas presents (the soundtrack, PPPPPP, is available here for $4, by the way). VVVVVV is honestly a tremendous game in a tiny package, and I would recommend it to anyone willing to take it on. If nothing else, the game's regular price is now $5, down from the original $15 when it was first released. To quote someone else (sorry I can't remember who specifically), there's really no reason not to own this game anymore.
Assassin's Creed II
Right then, here's something completely new: I'm about to recommend a game I don't even own. (Yet. Hopefully. Here's my Steam wishlist, by the way. In case you were curious.) A friend started me off playing Assassin's Creed II on his PS3 after I expressed interest in the series, particularly after Assassin's Creed: Brotherhood came out a month or two ago. I'm probably only three hours into playing the game, but I've been completely floored by what I've experienced so far. Without spoiling too much of what I've experienced so far (though why bother avoiding spoilers, I'm already months behind on this one), one of the things I've loved so far is the stealth aspect of the game, something I didn't encounter (properly, anyway) back in that Thief game long ago. Sneaking around is simple, but still tricky to master, in that way that makes you feel like a champion when you finally pull it off. Factor in a pretty involved storyline, fan-freaking-tastic graphics, and a bowl of popcorn (or at least, that's how playing it at my friend's place has gone), and you've got one pretty amazing game, based at least on the three hours I've played of it so far.
In the interest of fairness, I will throw out a couple of disclaimers, seeing that I haven't played this game in its entirity yet. In my first stealth-based mission, which I loved so dearly, it turns out that in order to complete the task (which required me to kill a certain person, sneaking up to them), it turns out that after three attempts to make the kill in perfect stealthful-ness, the proper way to finish the quest is to break cover for the kill, then roll a cutscene in which you declare your vengeance on the town to everyone watching. I'm so happy I spent all that time trying to be noticed just for it to be blown for the sake of a cutscene. I hope that sort of incident (sacrificing normal or desired play to set up a cutscene) doesn't happen often in this game, as that instance left a sour taste in my mouth.
Another minor quibble I have is simply personal; I hate playing sequels to games before I play through the originals. There are exceptions of course, like Left 4 Dead 2 (where the gameplay is pretty much the same as the original) and Team Fortress 2 (where the game experience is way different from the original... how's that for a double standard?), but I couldn't/can't help feeling like I'm missing something by not playing the original. From what I gather from multiple sources though, The original Assassin's Creed got stale rather quickly, and AC2 improved on it tremendously, while AC:Brotherhood maintains the high standards of AC2. That all said, I'd still like to at least play through the original Assassin's Creed, but with the opportunity to play through AC2 presently at my fingertips, I won't hesitate to jump on that. Going by what I've experienced so far, I'd list Assassin's Creed II in my recommendations.
The "Other Recommendations" Lightning Round
The Ball - Steam link - demo available - JiG Review: I once heard someone describe The Ball as what Portal would be like if it ran on the Unreal engine. I'm not familiar enough with the latter to really be sure, but it's definitely got the puzzling heart that Portal had. (Thanks Thomas!)
Puzzle Dimension - Steam link - demo available - JiG Review: Puzzle Dimension is like a lot of games where you've got to grab some loot and make it to the door, but with the extra twist of levels that play with gravity and other little spacial tricks. Definitely a challenge, but a somehow relaxing one at that.
Magnetis - Steam link - demo available: Simple-yet-hard Dr. Mario-esque puzzle involving connecting magnets to clear blocks. Good fun in solo mode, but I want to try this in multiplayer sometime.
That essentially wraps up my recommendations for this year's Steam sale. Again, I'd suggest rereading last year's list, and also see some of my reviews over the past year for more picks. And as a final reminder, if you'd like to show your appreciation for my helping your game-buying plans, I'm sure there's something you could do to thank me. (That's not too tacky of a way to end off a post, is it? Desperate pleading?) Merry Christmas, everyone!