Braid

I recently downloaded the game Braid via the Xbox 360 Live Arcade, and just finished up playing through it. I can't say enough good about this game. It is a little indy game by a small team (essentially two guys), and it is very much worth the $15 bucks for it. I'd love to see more creative works like this. It is hard to tell from still photos (which might even look kind of childish and silly), but it is a very beautiful game, with painterly graphics and a fantastic score. It is mainly a platformer (with heavy nods to Super Mario Bros.) but includes the use of time-manipulation to collect puzzle pieces that help you proceed or add to the story.  The story and approach is so refreshing: it is well thought out, it is thought provoking, and it is mature.  I can see how some people might be put off by the ambiguous, arty story, but it is challenging (story wise and many of the puzzles) and you'll be rewarded by well earned a-ha moments (again in the story and from solving the puzzles).  Without spoiling anything, I was at first kind of confused and underwhelmed by a change of style of the last level, but then when I figured out what was going on, it completely floored me and made me appreciate the game much more.

Other recent games (not so thought-provoking):

• Oblivion: Shivering Isles - Fairly recently finished this. If you are looking for a game (an older one) that will give you a ton of hours of play, it is Oblivion.
  
• NCAA Football 2007 - I found this for $5, so I bought it. Oh, Iowa State, why can't you be more powerful?
  
• Soul Calibur IV - Far from thought-provoking or life changing, the Soul Calibur series is still a fun bit of mindless fighting.