"Provably fair" is not a slogan — it is a property you can test. Each round commits to a random value before you play, so the result is fixed by math you can re-run, not by a server deciding after your bet.
Commit, reveal, reproduce
Before the round, the system commits to a server seed (via its hash) and mixes in a client seed and a nonce. The outcome is a pure function of those inputs. After the round the server seed is revealed, so you can hash it to confirm it matches the earlier commitment, then recompute the exact result.
Why the house cannot cheat
Because the commitment is published up front, the operator cannot swap the seed to change your result without breaking the hash — and you would catch it instantly. The math is public; only the pre-committed randomness drives the outcome.
Try it
Open any Original, play a round, then use the verifier to paste the seeds and nonce. You will reproduce the same outcome. The same approach secures The Ruffler and, in time, the on-chain settlement paths.