HEY! I've been playing Portal 2 and I really love it
...I even re-installed Portal thinking I should at least attempt to finish it, lol.
Have almost finished the co-op extras with Stryfe, too, and will probably try some of the workshop things afterwards.
I think these games are the only thing that can make me like puzzles. lol. It's just the greatest feeling when you figure out what to do, fly through the air and don't die.