Provably fair, by construction

Decentralized & verifiable by design

SolanaJack is a decentralized casino that lives entirely on the Solana blockchain. There is no server picking winners and no company holding your money: every deposit, every card and every payout is a public transaction anyone can inspect.

Blackjack

• Your bet is locked before any card exists. Creating or joining a game asks the random oracle in the same transaction as the deposit, and each player gets their own value, so neither hand is drawn from the other's.
• Every card comes from a block hash that does not exist yet when you click. That is what stops anyone cancelling a move after seeing a bad card. A card never recorded within about three minutes counts as a bust, so stalling gains nothing either.
• Player 1's hand is hidden by a secret only their browser holds. While the game runs, only the number of cards taken is public.
• At settlement the secret is revealed and checked against the hash committed at the start. The contract re-deals the hand from the oracle's value, the block hashes and that secret, then pays out, and anyone can repeat the same computation.

Roulette

• Your chance is your share of the pot, exactly. The draw picks one lamport out of the pot and pays whoever staked it. Stake a fifth, own a fifth. That is arithmetic, not a number we choose.
• The random value is requested only after betting closes, and the contract proves the request was made in that very block. So nobody can find out what a request would draw and only then use it.
• Anyone can spin the wheel. Our keeper does it within seconds, and for about two minutes afterwards any player can do it instead. Whoever sends it, the contract pays the player the value picked; naming anyone else is refused.
• If the oracle never answers, every stake comes back in full: no fee, no winner. Same if you are left alone at the table for an hour.
• The payout is public and drains the escrow. The round pays the random oracle a fixed 0.0005 SOL for the draw; the winner takes everything else minus the flat 1% edge, including anything anyone sent to the escrow address.

Trading duels

• Your trade carries no price. The contract records only that you traded and when. The price is written in afterwards, by a separate step anyone can send.
• You fill at the first price published after your trade lands. So holding a signed transaction to see which way the market moves is pointless. The price you get did not exist when you signed it. And only the earliest price after your trade counts, so nobody can shop for a better one later.
• Every price is checked against Pyth, the oracle most of Solana's lending and perpetuals markets price on. A price that disagrees with Pyth, is stale, or is signed by the wrong key is refused outright, and the contract then simply reads Pyth itself.
• Your book is sealed until both trading windows are over. The chain holds a hash of each trade while you play, and at reveal the contract refuses any book that does not match those hashes exactly.
• Closing prices cannot be cherry-picked. Open positions are valued at the first price at or after the minute your window ends, trading stops ten seconds before it, and a recording made closer to that minute replaces one made further away, so everybody ends up at the same number.
• No leverage, and shorts are cash-secured, so equity mathematically cannot go below zero. Nobody can ever lose more than they staked.

Check it yourself

• Open any game, round or duel on a Solana explorer. The deposits, the oracle's answer, every move and the final settlement. Payout plus the 1% edge, are all public and permanent.
• The escrow is keyless. There is no private key for it anywhere in the world; only the contract's rules can release what is in it.
• Settling is permissionless. If we disappeared tomorrow, any wallet could finish your game and pay you. The "Settle now" button in the app is just one wallet doing exactly that.