1/3
4 Years of Service
Because they're using assets, scenes, and animations created inside of a game that is itself separately sold on Steam by the successor of the company who created it (Honey Select 2). It's the same reason you couldn't, for instance, make a game purely out of screenshots from you playing Skyrim or Baldur's Gate 3, or The Sims, or something, and then sell it on Steam.well that sucks. Do you know why?
Personally, I think it's silly since Illusion doesn't even exist as a company anymore, but the Honey Select IP is still owned by someone, and it would have to be licensed by them to the dev trying to sell it on Steam, which they have historically never done AFAIK.