Players enter a world with "some kind of physics". The implementation is hidden (sound familiar?), you and/or your team earn points by proposing and testing models to predict experiments, etc. It's set up to be actually achievable (not familiar).

Maybe you self-host an api server and issue crypto credentials to game participants (like "http" and "api key" but way faster and smarter).

You could also set up puzzles that other clients can try to solve. Probably-maybe there can be some zero-knowledge proof of a solution. At least the "api" for determining winners and points and such would have to be simple and can't really depend on the implementation. "A pass is a pass".