The developers of Dwarf Fortress rejected a six-figure offer for the right to use the name because they were concerned about "cheapening" the brand.
Dwarf Fortress is a remarkably deep and famously dense strategy/rogue-like, presented entirely in ASCII graphics, that was first released in an alpha state in 2006 and is now up to version 0.34.11 - which is to say, not yet fully released. It's the work of two brothers, Tarn and Zach Adams, who estimate in all seriousness that version 1.0 will probably be ready in about 20 years; and they take the project seriously enough that when an unnamed publisher came around with a six-figure bag of money, they said "no thanks."
"There was an offer to use the Dwarf Fortress name - sort of 'Dwarf Fortress: Subtitle' or whatever - they wanted to brand one of their other games. And the amount of money on the table was six figures," Tarn Adams told Gamasutra. "When you look at that you think well, there's trade-offs. Does the brand get cheapened? Are you deceiving people? As long as they're clear this is not Dwarf Fortress or whatever, and this is not Dwarf Fortress with graphics, as people call a lot of things that are coming out these days. As long as you're upfront and honest, there's not technically a problem with that - it's our brand to piss all over if we want."
Despite that rejection, Adams said that signing a deal with a publisher isn't necessarily off the table and might actually be good for the game and fans, pointing out that if they didn't have to worry about money they could spend even more time working on Dwarf Fortress. But they also run the risk of actually losing money over the long run.
"If people saw that there was this other thing out there, we considered in the worst case scenario, then the contributions from people would just dry up, and we'd be sitting with this lump sum that would not have added up to ten years' salary or whatever," he explained. "So do we want the stress of having to search for a new IP, or a new angle all of a sudden? We have some name recognition to be able to do that kind of thing perhaps, although it's a very chancy thing."
Adams also sounded dubious about the idea of putting Dwarf Fortress on Steam, saying they'd do it if there was demand from the fans but otherwise expressing little interest. "I don't know enough about it, and it's the kind of thing that, from the years of inertia, we don't have these business instincts that kick in and say, 'Yes, we need to get on that'," he said. "So it's sort of the thing where, if enough people bug us because they want Steam to track their user hours or whatever... if our current fan base wants it on there, it'd be more of the kind of thing we'd be interested in, rather than increasing our audience."
If you're not familiar with Dwarf Fortress and think you might like to be, you can find out more about it and follow the development at bay12games.com.