Win big with the
lowest unique bid.
Everyone secretly bids on the same prize. The catch: the winner is whoever picks the lowest number that nobody else picked. Bid smart, not high.
Lowest
unique number wins — high bids almost never do.
Sealed
bids are hashed on-chain. Nobody sees your number.
Winner
takes the whole prize pool. One bid per round.
It's a lowest unique bid auction — a game of nerve, not budget. Pick too low and someone else picks it too (you cancel out). Pick too high and someone undercuts you. The sweet spot is the smallest number you think the crowd will leave alone. Unlike a lottery there's no dice or random draw — the outcome is decided entirely by how the players collectively reason about each other, which is exactly why it's treated as a game of skill, not pure chance.
Game theorists call the toy version LUPI(Lowest Unique Positive Integer). It has a known Nash equilibrium: there's a cutoff past which bidding higher is never worth it — with ~100 players it sits around 31. Sweden's state lottery even ran a daily LUPI game (“Limbo”) that pulled ~50,000 players a day. Here, bids stay secret via a commit–reveal scheme and the contract settles the round on Arbitrum.
How it works
1 · Commit
Pick a whole number in range and commit it as a sealed bid. Your number is hashed on-chain — hidden from everyone, including you.
2 · Reveal
When the timer ends, all bids are revealed at once. The contract groups them and throws out every number that more than one person picked.
3 · Win
The lowest number nobody else matched wins the prize. No unique bid? The round rolls over and play continues.
Feel it in 10 seconds
No wallet, no money. Pick a number, watch rivals join with sealed bids, then reveal to see who took the prize.
Live demo · no wallet needed
Pick the lowest number nobody else picks
You're bidding on a $1,000 prize. Choose a whole number from 1 to 10 and seal it.
Ready for a real round?
Live auctions are running now on Arbitrum testnet. Connect a wallet, grab test USDC from the faucet, and seal your bid.
Enter the arena