After the "mini game" ball jumping thing, I got stuck by turning around and entering some menu which I couldn't exit. I really enjoyed it up until then though. I'll probably come back to this at some point to finish it. The atmosphere and feel you set up is really interesting, and the aesthetic isn't something new, but you take it far enough for it to feel fresh and interesting. I was pleasantly surprised by this project and hope to see you complete it.
P.S This isn't a prototype. It's an alpha, a prototype is a test to see if the core concept works or not. very often with simplistic graphics. With heavy focus on the mechanics. This looks more like it's in the alpha phase, AKA feature-incomplete and buggy.