A complicated history for this one, with the developer Rocket Jump Technology no longer existing as a business. The previous iteration of the game named King under the Mountain went open source back in January 2024, and now what was to be the big revamp is also open source.
A Rimworld style game wouldn’t be the worst for the open source model. It certainly doesn’t have the problems open development brings for story-driven games with spoilers.
It helps that Mountaincore, while clearly incomplete, seems to have a solid foundation.
What be great if someone picks this up and fleshes out the experience.