OmniLotto

OmniLotto is a cross-chain, no-loss lottery protocol that turns savings into a game. It unlocks billions in dormant capital from the XRP and Bitcoin ecosystems, allowing users to deposit assets, earn yield, and win prizes without ever risking their principal.

Unlike traditional lotteries where players lose money, OmniLotto pools user deposits into DeFi yield sources (like Aave). The generated interest forms the prize pool, which is awarded to one lucky winner each week. Everyone else gets their full deposit back.

We address the fragmented liquidity problem by unifying users from Flare (XRP), Citrea (Bitcoin), and EVM chains into a single, provably fair protocol. By leveraging Flare's FTSO for real-time pricing and secure randomness (both Flare Random and Bitcoin block hashes), we ensure a fair, transparent, and decentralized experience.

OmniLotto is built on a hub-and-spoke architecture with the core logic deployed on Flare Coston2 and Citrea Testnet.

Technological Stack:

Flare Network Integration:

• FAssets: We designed the system to accept FXRP (synthetic XRP) as a primary deposit asset, -bridging the XRPL to DeFi.
• FTSO (Flare Time Series Oracle): We integrated FTSO to fetch real-time XRP/USD and BTC/USD prices. This allows us to normalize the value of different prize pools (FXRP vs. cBTC) for a unified leaderboard.
• Flare Smart Accounts (ERC-4337): We implemented gasless transactions to onboard Web2 users. A custom LotteryInstructionHandler contract allows users to interact with the lottery without holding native gas tokens.
• Flare Secure Random: We utilized Flare's enshrined RNG for fair prize draws on the Flare side.

Citrea Integration (Bitcoin L2):

• We deployed a native CitreaLotto contract that accepts cBTC.
• Bitcoin Randomness: To ensure fairness for Bitcoiners, we implemented a custom RNG mechanism using blockhash(block.number - 1) from Citrea, effectively using Bitcoin's own security for randomness.

Notable Hacks:

• We had to build a custom "Instant Win" mechanism for the hackathon demo to allow judges to simulate a week-long lottery draw in seconds. We also engineered a client-side filtering system to render two completely different dApps (Flare vs. Citrea) from a single codebase to streamline maintenance.