What is checked
Chain integrity. Every round's server seed comes from a hash chain fixed before the chain's first round. The revealed seed must hash (SHA-256 of its 32 raw bytes) to the link published before it, so the seed was not picked after bets were placed.
Signed terminus. Hashed forward once per chain position, the revealed seed must reach the chain's last link, the terminus. The terminus was signed and published before the chain's first round; this page checks that signature (ECDSA P-256) against a public key built into this verifier, never one sent by the server. A seed far into a chain can take up to a few seconds per million positions to check.
Outcome integrity. This page recomputes the result in your browser with the
same code the game server runs: HMAC-SHA256(key = server seed, contribution:round_id:nonce);
the first 13 hex digits give R, and R / 252 goes through the game's published formula
with the round's RTP and cap.
Both checks use only the published record shown with each result, so you can repeat them with any SHA-256 and HMAC tool.