Provably Fair

Last updated 2026-10-31

Nobody, including us, can change a round once betting opens. You can check every round yourself.

How it works

1. Before betting opens the house picks a secret random seed and publishes its fingerprint: the commitment, which is SHA-256(seed). It is shown in the game next to the round number.
2. The seed decides the round. The bust point comes from the seed and the round's house edge, with the published formula below.
3. After the round the seed is revealed. Anyone can hash it and see that it matches the commitment published before the bets, and recompute the bust point.

The formula

The seed is 32 random bytes, written as 64 hexadecimal characters. The commitment is the SHA-256 hash of those bytes.

1. Compute HMAC-SHA256(key = seed bytes, message = "run-or-bust/crash").
2. Take its first 52 bits as a whole number n, and let u = n ÷ 2⁵² (a number from 0 up to, but not including, 1).
3. The bust point (rules version 5) is the largest multiplier x on the 0.01 grid with 0.95 × x^−1.44 ≥ 1 − u; a result below 1.00x counts as 1.00x. It is computed with whole numbers only: the largest c (hundredths) with c³⁶ × (2⁵² − n)²⁵ ≤ 95²⁵ × 2¹³⁰⁰ × 100¹¹, so every computer gets exactly the same result.
4. A bust point of 100.00x or more means the runner finishes and bets still riding pay 100.00x. (Each round records its rules version. Versions 1–4 use RTP ÷ (1 − u) instead, with RTP the round's return to player; versions 1 and 4 count a result below 1.00x as 1.00x; versions 2 and 3 let a round end below 1.00x, from 0.70x. Versions 1 and 2 finished at 10.00x.)

So the chance of reaching any multiplier x is 0.95 × x^−1.44 (version 5) or RTP ÷ x (versions 1–4). There is one red light per round, at the bust point. (Rounds before 11 October 2026 also had feint red lights, from HMAC-SHA256(seed, "run-or-bust/decoys"); they never changed the bust point.)

Check a round

• In the game: open Rounds. Each finished round shows its commitment and seed, and your browser checks them. A ✓ means the seed matches.
• Anywhere: the list of recent rounds with their seeds is public at runorbust.com/house/rounds. Hash the seed with any SHA-256 tool and compare it with the commitment.

What the seed does not decide

Your result depends on the bust point and on when you cash out. The seed does not know who bet or how much, and house bots never see it before the round ends. The round max win (see Game Rules) can cash players out early in a very big round, but it never moves the bust point: the seed alone decides it.

Questions about a round? Note the round number and write to support@runorbust.com, or see Complaints & Disputes.