The /agdg/ in me finds this discussion on Saeko interesting. On paper, I think the best way to go about making a "mainstream" macrophile/microphile game is masking it as some sort of fusion of Chibi Robo or Tiny Kin and Stardew Valley/Rune Factory. Play as like a 6 inch/~15cm tall doll character in a town/area solving problems and interacting with normal sized people. Maybe throw in some invasion of tiny demon or ayys for a stronger action element. If you want to try and get some extra money from fujos/yumejos, and make female vtubers go uooogh, you can throw in some male love interests.