I've come into this jam quite late, I actually had exactly a month (and I think like, 3 hours?) when I joined in fact. But I've decided to make a LUMEN game inspired by Homestuck, and more specifically the only aspect of Homestuck that I still enjoy anymore, the concept of the SBURB game, expanded upon in the amazing SBURB Glitch FAQ fanfic.
Players of Homeward are Bearers, children ripped from their homeworlds to 'play' in The Game, a sadistic, multiversal game about maturity through any means. They go on quests throughout custom made planetoids designed to challenge them, whilst wrestling with an element that is in conflict with their greatest flaws, with the ultimate goal of creating a new universe, or reviving their old one.