Provably fair — how the tide decides
The tide is Blake's testnet4 — the BLAKE2b hardfork of Bitcoin, which parted from
plain testnet4 at block 150,308 — followed by
mempool.guide. Runs
committed before Reef Run moved to Blake settle and verify against plain testnet4, the chain
they were committed to.
In Tide mode your run names a Blake testnet4 block that does not exist yet.
When it is mined — and one more block confirms it — the reefs are placed by
sha256(blockHash | mark), your mark being a random nonce fixed when you
committed your course. Nobody, not even this page, knows where the reefs lie before the
tide comes in, and anyone can recompute them afterwards from public chain data — the
verify ✓ in the log does exactly that, in your browser. If a deep reorg ever moves
a settled block, verify says so instead of pretending.
You shape your own odds: more reefs and longer courses both raise the payout, and every
combination carries the identical 3% house edge — the maths is open in
reef.js, pure and testable.
Practice mode is seeded locally and marked as such — instant, but not provable.