One PC game I've been playing from time to time since about one year is
Starcraft 2. There are many quite fascinating aspects of this game which I like: For example the now huge international Starcraft 2 scene with all the tournaments and pro gamers. Every day it's possible to
watch new, interesting commentated games between professional gamers, and interestingly, that's much more entertaining than watching for example a plain old sports event like football.

From a programmers view, SC2 also has some interesting technical features, like how the multiplayer and replay functionality works. Behind the scenes, it's obviously a simple deterministic state machine running the game, and only key and mouse input events are sent between players, making the multiplayer game work on even slow internet connections. Replays are saved in the same way. I always wondered if it is possible to play replays of old versions of SC2 at all, and how the programmers manage to let the state machine work with those old files when they changed lots of mechanisms and values in new versions. Yesterday I noticed that they don't: When you replay an old game, Starcraft will then launch the old binary .exe of your game, to play it back.

The only thing I don't like about this game is that I'm absolutely horrible at it. I'm quite ok when playing with other people (I'm platin in 3v3), but in normal, 1v1 matches, I absolutely suck. After playing it a few hours every week for one year, I'm still in the silver league. I know a few nice builds which work, I am able to macro up (I play zerg) and what unit compositions are useful against what kind of enemies. But I fail very often. Interestingly, this is what lets me keep playing the game, and try getting better.
I wonder what the reasons are for my failure. Being 32, I think maybe I'm maybe to old, and too slow for this game. Also, I've noticed that the strength of my opponents are different based on the day in the week and the time of day. On weekends, my opponents are usually unstoppable, although playing silver. When I play a match in the evening during the week, I have no problem defeating even gold or sometimes platin players. Maybe I'm playing at the wrong time. Or maybe I simply suck. :)
Anyway, it's a fun game, and I can recommend trying it out. Now back to programming. That's what I'm a bit better at. ;)
The real question is what you did to imrpove?