You know what's kind of like Dwarf Fortress, but not really, and is totally fucking awesome?
Minecraft. It's developed by one lone lunatic and is currently in Alpha. It has: procedurally generated 3d landscapes that can look absolutely stunning on their own, let alone once you start crafting and building glass/stone/wood monoliths filled with lava towering into the square clouds.
There's caves, mountains, forests, and realistic water, lava, and lighting. Not to mention monsters, an extensive (though unintuitive)crafting system, and multiplayer which is currently being tested in somewhat glitchy, barebones sort of way.
Oh yeah, and the worlds it generates for you can be up to eight times larger than Earth (not that any of our computers could handle such a world anyway, but it's possible)
Anyway, it's fucking sweet, and I highly recommend it. Especially since it's only $13 right now (though it will be more later) and for your money you get the game forever, DRM-free, including all future updates, and the ability to use custom player skins, I guess. You can download the client or play it in-browser, but I had a hard time trying to get the browser version to work.