Thanks so much for this comment; exactly what I had in mind without being able to put a pin on it, the 3D screensaver!!

At this point there is no backend. Everything is generated from a single seed. A couple of 3D assets and rules for generation (like indeed rarity levels). There are stairs, corner stairs, and double-height rooms, and I am adding more variety when I feel like it. Also, different environments (like dungeons or backrooms) have different raily rules.