> For the complete documentation index, see [llms.txt](https://atomrigslab.gitbook.io/what-is-leedo-project/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://atomrigslab.gitbook.io/what-is-leedo-project/blockchain/on-chain-raffle.md). # On-chain Raffle ### What is Blockchain on-chain raffle? Random numbers or random selection of winners or whitelisted participants should be as fair as possible. Using an oracle on a blockchain is an appropriate solution, since the choosing entity should not be involved in the decision. In the Leedo project, in the initial minting process, the project picked one winner of each event and sent Leedo tokens and ETH if a specific condition is met. In the on-chain raffle, one of the cards minted at the event was randomly selected and Leedo tokens and Ether were sent as prizes to the user who minted the selected card. A total of 20 events were held, cards were randomly drawn, and Leedo tokens and Ether were sent by the contract according to the rules. The on-chain raffle contact in the Leedo project is: **Leedo Project on-chain raffle contract** * The NFT of Fortress Games, which was heavily invested in the Leedo project, also used an on-chain raffle to select 9 winners and gave them a foundry card as a prize. The on-chain raffle used in the Fortress game is also a contract supported by the Leedo project. **Fortress Game on-chain raffle contract** *