Having deeply enjoyed One Potion Please!, this proof-of-concept prototype highly engaged me, and I'm excited to see how this concept develops!
I saw it was listed as one of the first hints, but the indication that items are permanently available after picking them up could be a little clearer. I made the mistake of thinking that I'd have to interact with the Berry Amulet's prior wearer every time I wanted to use it in a run, and that prevented me from messing around to find its intended solution for a few minutes longer than probably intended.
If the game this would spin into has all three character classes from OPP! available in the character creator (Warrior, Rogue, Magic-User), if it could be feasibly implemented, I think it'd be neat if they each had different solutions to the meta puzzle of each floor, potentially spun as "difficulty modes," or just alternate routes.