OH one more thing, I think I've seen some things where comics artists will have backers added in background scenes. Not sure if there's a chance backers could add lines of dialogue or something cheesy that doesn't change things too much but otherwise not really sure what could be done as a 'reward'.
Well - Giving the 18+ content to backers for free, while other consumers have to pay extra for it looks like a decent reward to me.
Just make that 18+ content available for a decent price to other buyers that have committed the crime to be "late at the show" looks like punishment enough for those horrible, horrible people that noticed this VN too late (like me). But in stead of getting some extra money, the developer have chosen to get no money at all.
But I really respect that choice by honoring those wishes, and not buying this VN at all. I am sure that must be a satisfying feeling for the developer.