The only runtime dependencies are pg and ws. So there is no game engine or framework used at all. There is also a mobile wrapper for the app store, but it's not released yet.
Even the massive world is completely procedurally generated. It's random every day, which means there are tons of rules around how it generates. Would love to answer any questions about how it works or processes.
(no profit is made whatsoever btw - this is purely a test of Claude's skills + a hobby)