If you want to make it a multiple players then you will need a character creator with many options and features (like Artificial academy 2 and koikatsu games), and separate clothes instead of one set
Adding and focusing on both relationships and NSFW instead of gore will actually work, like replacing Killing with ntr (emotional pain instead of physical), like accidentally a player finding their gf/bf cheating with another player in an empty class or anywhere else away from everyone, get angry or if they ok with it they can join in a 3p fun
also adding a mini fighting game ONLY available for the male players in multiplay, when two guys liking the same girl they can fight and whoever win get the girl (if she accepts of course lol)