crosschain casino

Cross-Chain Casino is a decentralized gaming app that lets anyone place onchain bets from any supported chain and execute the wager on a destination chain in one click. It uses the Avail Nexus SDK to abstract bridging, routing, and execution so players don’t have to pre-move funds or switch networks. The result is a smooth, multi-chain casino experience with provable settlement and transparent game rules.

What it does

Lets a player stake native or ERC-20 assets on their source chain (e.g., ETH on Base) and automatically Bridge & Execute a bet against a game contract deployed on a destination chain (e.g., Polygon).

Handles the bridge leg and the contract call atomically via Nexus intents, returning the outcome and funds without manual bridging.

Pays winners instantly from the destination contract; optional post-win intent can auto-return winnings to the player’s origin chain.

How it uses Avail Nexus SDK

nexus-widgets powers wallet connection, cross-chain token selection, and a Bridge & Execute button for the betting flow.

nexus-core (headless) can be used for advanced intents and safety rails (slippage ceilings, gas budgets, allowed routes).

The app demonstrates a full cross-chain intent: sourceChain funds → bridge → execute placeBet(guess) on the destination contract → emit outcome → payout.

Game mechanics

Initial game is Dice: player guesses 1–6 and stakes an amount; the destination contract computes a roll and pays out if the guess matches.

House edge and payout ratios are configurable; transparency is enforced via open-source contracts and onchain events.

For hackathon speed the demo uses simple block-derived randomness; roadmap includes Chainlink VRF or equivalent verifiable RNG.

User flow

Connect wallet, pick source chain, token, amount, and game guess.

Click Bridge & Play; the Nexus intent bridges funds and executes the bet on the destination chain.

The contract emits Bet events and immediately pays out on win; the UI shows status and transaction links.

Why this is useful

Removes the biggest UX friction in Web3 gaming: pre-bridging and chain switching.

Unlocks unified liquidity: players can use assets where they already are.

Provides a template for any multi-chain game or prediction market to go cross-chain with minimal extra code.

Cross-Chain Casino was built from the ground up using Vite + React + TypeScript for speed and modularity. We started with the official Avail Nexus Vite template, wiring in @avail-project/nexus-core and @avail-project/nexus-widgets to handle all cross-chain intents. The frontend uses Wagmi + Viem for wallet and chain connectivity and shadcn-style UI for a clean look.

The core feature—placing a bet from one chain and executing it on another—runs through the Nexus SDK’s Bridge & Execute workflow. Inside React, we wrapped the SDK in a custom NexusProvider component that initializes the Wagmi config, Query Client, and the Nexus Provider. A dedicated BridgePlayButton component builds a full BridgeAndExecuteParams object that specifies source chain, destination chain, asset, and the function call to our game contract.

On the smart-contract side, we deployed a minimal DiceGame.sol written in Solidity ^0.8.20. The contract uses pseudo-random block data to roll a number 1-6, emits a Bet event, and immediately pays out on correct guesses. It’s simple but ideal for demonstrating Avail’s cross-chain execution—bets bridged from any chain call placeBet on this contract.

We kept the app lightweight:

Frontend → Vite + React app hosted on Vercel.

Blockchain layer → Any EVM chain (tested on Base ↔ Polygon) running the DiceGame contract.

Cross-chain logic → Avail Nexus SDK handling all routing, gas abstraction, and execution.

Hacky but fun bits:

Used Nexus widgets’ internal hooks directly to preview transaction states and surface live bridge status.

Faked a “unified balance” view by aggregating Wagmi useBalance across chains for demo impact.

Added instant payout visualization by listening to the Bet event via Viem websockets.