Add in a very dark fantasy setting, more randomness in environments/missions than your average ARPG, and multiple characters within the same "run"...

Indeed, but I think the game would be even better if it would be balanced around that :)

It's the classic Necromunda campaign issue. Failure leads to harder time playing which spirals. To play well this must balance the opposite - classic rubberbanding solution - after failure it should be a bit easier to claw back.

Yes, but the game is not designed for permadeath and is unnecessarily frustrating in many aspects. You can play any game permadeath, but most are less or more frustrating.

Visuals think Ishar, combat think M&M 4-5, with DCSS-style richness of random dungeons and JH-style streamlining.

I need a genre that I'm vaguely familiar with though, BH is farr from it :P

I'd veer to single character myself also.

There isn't much overlap in the design space :P

tldr - Unity :P

The metric should be the percentage of released indie games that made enough profit to allow the creators to fund the next title.

"Hey kid, don't get discouraged - after you fall a couple of times trying to ride the bike, I'll give you training wheels, and a while later a trike. Tomorrow you'll get a quad and feel awesome having mastered driving!".