Why not try to "externalize" the game data files, like sprites, stats, mapgen, etc- essentially make it moddable and do some kind of openDev or community collaboration thing instead of fully open-sourcing it? That seems like it could work. Also, with Unity's new runtime fee thing, have you considered moving to another engine? There aren't many sci-fi roguelikes out there, so EFA has the potential to be something really truly special.