Dwarf Fortress is arguably one of the most hardcore examples of hobby software out there. For those who don't know it: think of Minecraft (Note: this kind of puts the world in reverse; Dwarf Fortress has been around for much longer than Minecraft, and quite likely has taken its inspiration from there.) but without the fancy graphics and with the most extreme form of generative gameplay you could imagine. It features a randomly generated world which includes lots of different creatures, races and biomes, and which even works out a few thousand years of history.
If the above screenshot looks like a random bit of ASCII art you are easily forgiven. Dwarf Fortress is not an easy game to learn (try this two and a half hour tutorial on Youtube if you're curious), but it does offer some deep gameplay. Probably the most well-known example of that was recorded in the Boatmurdered stories. Even if you don't intend to play the game, those stories are well worth the read.
Perhaps the most amazing thing is that the main developer of Dwarf Fortress, Tarn Adams, makes his living from his work on the game even though the game is a free download. Tarn has such a loyal following of gamers that they simply donate money so that he can keep expanding Dwarf Fortress. In return for their support they also get a hand-drawn rendering of any scene from the game they want. Don't believe it ? Here's a recent interview with Tarn by the NYTimes, which includes some of these drawings.
I can only conclude that working on Dwarf Fortress takes dedication and a little madness. But you have to admire the result.
This is a first try for a Make Install post. Feel free to give pointers to help improve this category; and if you have ideas for a future post then don't hesitate to let me know.