01 / Mental Poker
SHUFFLE
SHOWDOWN
Five cards. One mysterious rival. Two locked shuffle seeds. Play the hand, then investigate whether the deal was fair.
Lock in independent random seeds with real SHA-256 commitments. Pick your cards and wagers, face the dealer, and earn an audit bonus by catching a forged opening.
BEFORE THE DEAL
Nobody gets to choose the deck alone.
The rival locks their random seed before you lock yours. Their shuffle seed is hidden until the final audit.
YOUR HAND
Risk your chips
A win earns your wager; a loss costs it. Higher cards win each duel.
Final boss / The audit
Was the shuffle opening authentic?
The rival reveals a seed and nonce. Your job: check that the revealed values match the commitment published before the deal. If the hash fails, reject the deal.
Published rival commitment:
Rival's revealed seed and nonce:
Run the audit to revealRecomputed from rival opening:
Run the audit to computeYour own published commitment:
Recomputed from your opening:
Run the audit to computeGenerating the rival's independent commitment…
Where this leads
From a sealed shuffle to verifiable protocols
Your SHA-256 audit can detect a changed opening, but it cannot by itself guarantee private card dealing, an authenticated opponent, or a verifiable shuffle. Explore the individual building blocks.
Safety boundary: Educational game with fictional chips and cards. Real SHA-256, fresh browser randomness and locally simulated participants. Never use this as a secure gambling, dealing, or money-transfer protocol. No accounts, network requests, ads or analytics.