A horse race betting dApp built for the Oasis Privacy4Web3 Hackathon.
Rose Derby is a horse betting "game", similar to real-world horse betting, except with simulated races using Oasis Sapphire RNG to determine the race results. What makes it interesting is that the participants are all completely private but the statistics and game activity is public, so it's obvious people are playing (and winning), but no one knows who is playing.
Players are incentivized to schedule and find participants for races by setting a % organizer "take" which awards them a percentage of the total betting pool on a race. Then once the betting window has ended, players are then further incentivized to call the "determine race results" function to compute the results with Sapphire RNG and receive an additional percentage of the pool.
The contract owner receives a fixed 2% of every pool, and also receives any winnings for races in which no bettor wins.
To build and deploy this project for yourself, you'll need to first deploy the Rose Derby solidity contract, then use the deployment address and output ABI within the Svelte frontend.
- Metamask
- NodeJS
The dapp is currently built assuming users have the Metamask Web3 Wallet extension and has not been tested with other wallets.
NodeJS with npm is used for project dependencies.
From the project root use npm to install dependencies.
npm install
Add a .env file to the project root with a single entry SAPPHIRE_TESTNET_PRIVATE_KEYS and add at least 1 private key that will be used for deploying the contract to Oasis Sapphire Testnet.
Use hardhat commands to compile the solidity contracts via:
npx hardhat compile
Run unit tests against the hardhat network, use:
npx hardhat test or npx hardhat coverage
To deploy the contract, ensure that the private key account added to the .env file has some Sapphire TEST tokens (can be acquired from the faucet) and run the following script via hardhat:
npx hardhat run scripts/deploy.ts --network sapphire_testnet
The output from that script will display the address of the deployed contract. In order to use the contract in the frontend, copy that address and add it as the value of the the RoseDerby JSON key inside ~\rose-derby-dapp\src\lib\contracts\contract-address.json
like { "RoseDerby": "{{put contract address here}}" }
Then copy the output JSON ABI file from ~\artifacts\contracts\RoseDerby.sol\RoseDerby.json and place it in the ~\rose-derby-dapp\src\lib\contracts\ folder, overwritting the existing file. You'll need to do this any time you make changes to the contract.
To prepare and start the SvelteKit frontend, change to the front end folder rose-derby-dapp, use npm to install dependencies and start the vite hotloader.
cd rose-derby-dapp
npm install
run dev -- --open
With the dapp running locally in a browser with Metamask installed, use the "Connect" button in the top right corner to connect your wallet to the Sapphire Testnet. You may then create races, bet on them, and determine the results.
Use the refresh and withdraw buttons at the top winnings panel to check and withdraw winnings or to withdraw awarded incentives.
Note: The refresh and withdraw feature require a signature as they use msg.sender in the contract function.
The dapp's incentive system encourages players to schedule and promote their own races in order to increase their organizer % take. Get as many players as you can to bet on your races, and use a large caller incentive % to encourage others to run the results transaction.
By using Oasis Sapphire, the contract's design provides anonymity to players, as well as the contract owner.
A live demo can be seen at:
https://derby.brosette.dev/ or https://singular-sawine-69fd83.netlify.app/
This project is licensed under the MIT License - see the LICENSE file for details.