I gave Dwarf Fortress I solid try several months ago. While I was enjoying it, I made the mistake of going away from it for a while. It's not an easy game to jump back into, and is renowned for it's steep learning curve. The wiki tells you everything you need to get into it though, and it's definitely worth trying out. I'm thinking of taking another run at it, the game does some real cool stuff.
Lazy Newb Pack
(good way to get started, has some popular tile sets)