The game is called Dwarf Fortress, and it's a simulation game. It's very much like The Sims in that your organizing and controlling a group of units as if your a god. On the same note it's also very similar to MineCraft, although much more complex.
The game is free, and developed by Bay12 games. The game's main website can be found here:
Personally I use this game package, it includes graphical tiles and some utilities:
This is the tutorial I learned to play with--the game is immense to say the least. It's a bit out of date now, but it should prove useful I think:
I hope some of you get into it! It's great for killing some time =P