The test finder doesn't need to be disable along side the vending machine, I just find it boring to JUST have the vending machine not work. It makes barely a challenge.
I could see the erasor being used like an oreo but I just don't think it would make sense to have this as an item in game. It wouldn't break anything to add it but I just don't like the idea of it in general.
Going back on the green chemical idea, making it have a random effect isn't that bad honestly now that I had time to think about it, there is still the problem of telling the player how it work (the icon could be the chemincal with a question mark on it), which brings me to the posters.
The posters won't be a thing for a while, I think since I'd rather focuse on some other part of game like making the school bigger (the second floor is small as f*ck and in the animation you can see that the school has 3 floors so yeah), when I'm gonna make the posters probably some in the hallways like "stay hydrate", some in cafeteria with like "finish your plate" and/or "clean after yourself", in library saying "quiet, people are studying", etc....
I think I will credit then, do you prefer me using something else then a screenshot of your itchio account ? (Cause I would rather have to take a screenshot of an other media account like Youtube, Discord,etc... not forcing you of course)