I’ve heard about this game for a while, but since they just recently updated it with a ton of new features - a functioning z-axis, making the game 3d, being the biggest change - I decided to give it a try. 10+ hours of gameplay later, I’m thoroughly hooked, and I can’t possibly recommend the game enough.
It’s essentially a sandbox world-building game. There’s no real “goal” aside from to survive as long as you can and build the biggest world possible. It uses ASCII graphics like a roguelike, but you can add in some graphical user-made tilesets if you’d like.
Info, forum, download link here: http://www.bay12games.com/dwarves/
The wiki (good, if a little light since they’re still updating for the new version) for the game: http://dwarf.lendemaindeveille.com/index.php/Main_Page
Check out the “my first fortress” link on the wiki, as well as the other guides. The learning curve for the game is strange; it’s almost incomprehensible for like the first hour, but once you realize that all your options are always laid out for you in the menu, you can pick it up quicker and quicker.