Joined: Dec. 2002
I think that Minecraft's 8-bit blocky lego dynamic is intensely beautiful and creative, and I haven't tired of it yet after playing for 3 months*. It's like Sim City, but with zombies. Don't check it out if you're at all at risk for obsessive behavior.
Portal and Portal II are really fun, and the cooperative problem-solving element of the latter makes it a real kick to play with my 11 year-old daughter.
Dwarf Fortress was fun to read about, but the game-play is so tedious that I seriously wonder if it's not an elaborate hoax.
But I'm really a SERIOUS PERSON who never wastes time on such non-productive silliness.
*Who am I kidding? I've been obsessed with Minecraft since December.