It works off PoW, so all you need is a vaguely working js/wasm runtime. It won't fail you if it detects you as spoofing user agent, or are running a "weird" browser like servo on freebsd (or whatever). All of this is "good" for being non-discriminatory, but it also means it's pretty easy for baddies to implement hardware accelerated solvers that can solve challenges orders of magnitude faster than any user can, and at a fraction of resources required (because they don't need a full browser).