Tableland Chess NFT

Herein lies an example use of Tableland's on-chain ACL to build an NFT and game application.

Overview

There are two main parts of this application, a Svelte app and an NFT. The Svelte app has the responsibility of enabling minting Chess NFTs, which are a chess game. This app is how games are played and it's also the animation_url metadata uri. This means that the NFT itself is a view of the game. If you want to see this in action checkout Game 0 on Opensea, or look at Game 0 in the App. note that to view the game in the app you need a browser that has a wallet connected to polygon-mumbai The NFT is based on the ERC-721 standard, and the metadata follows the Opensea standard. The metadata also leverages Tableland to create mutable metadata with on chain Access Control Logic defined in a Smart Contract. In Tableland this kind of ACL is referred to as a Policy Contract. For the chess game the Policy Contract ensures that game data can only be inserted by the players of the given game, and once a game has a certified winner no more moves can be made.

NFT

For some context, each game is an ERC-721 compliant NFT that has been extended to include four additional properties.

1. player1
2. player2
3. winner
4. bounty

player1 and player2 are the addresses of those players. winner is the game's winner, more on this later. Lastly bounty is an optional amount of coin that the winner will be able to claim. When someone wants to "make a move"(insert a row into the chess moves table) in a Tableland Chess game, the Policy Contract will first check that the address trying to make the move is a player of that game and that the game is active. If they are not a player, or the game already has a winner the insert will not be allowed. Note on the idea of a winner: Since the game is an NFT, along with players, it has an owner. The owner is the address that minted the game. The owner can indicate who the winner is. Once there is a winner, that addres can claim the games bounty if any has been added to the game. Because of the potential conflict of interests, the owner can only be a player if there is no bounty There is also an opportunity for either of the players to concede the game, at which time the other player will be set to the winner.

The related code can be found in the evm directory

App

The app has been built using Svelte, and is served as a static webpage that connects to Tableland via the Tableland SDK. Most of the related code can be found in the src directory. The application is also responsible for providing the content of the animation_url metadata property. Because of this, you can see the game's moves palyed in a loop on opensea.

Deployments

Polygon Mumbai

NFT contract address: 0xc5bab640203add5e28c01975de53758240354f8d Opensea: chesstoken

Developers

Running the app as a dev:

npm install
npm run dev

Build the app: Update the .env file with the details of your contract deployment and tableland tables. See the example .env file for details

npm install
npm run build

The output of the build will be in the public/ directory

Working with the contract: First ensure you have updated hardhat.config.js with the details of your deployment, and you have a .env file ready in the evm directory. See the example .env file for details

cd evm
npm install
npx hardhat run --network <network of choice> scripts/deploy.js

set the app baseUri:

npx hardhat run --network <network of choice> scripts/set-app-uri.js

Contributing

PRs accepted. For any bugs open an issue. If asking questions on stackoverflow please use the tag tableland.

Small note: If editing the README, please conform to the standard-readme specification.