Creeprchain

for installation and building, visit github

Minecraft Fabric 1.20.1 economy mod. Players deposit items at an ATM block and receive ERC-20-style tokens on an Ethereum-compatible blockchain. Tokens are visible in MetaMask.

Requirements

Tool	Version
Java JDK	21
Fabric Loader	0.19.2
Fabric API	0.92.9+1.20.1
Node.js	18+ (for Hardhat)
Hardhat	installed in blockchain/

Building the mod

./gradlew build

The output jar is at:

build/libs/creeprchain-1.0.0.jar

On Windows use gradlew.bat build

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Installing on a Fabric server

1. Download Fabric Installer and install Fabric server for Minecraft 1.20.1.
2. Copy build/libs/creeprchain-1.0.0.jar into the server's mods/ folder.
3. Download Fabric API for 1.20.1 and place it in mods/ as well.
4. Start the server once — it will create the config directory at config/creeprchain/.
5. Edit config/creeprchain/blockchain.json (see Blockchain setup).
6. Restart the server.

Installing on a client

1. Install Fabric Loader for Minecraft 1.20.1 in the launcher.
2. Copy build/libs/creeprchain-1.0.0.jar into .minecraft/mods/.
3. Copy Fabric API for 1.20.1 into .minecraft/mods/ as well.
4. Launch the game and connect to the server.

The client and server must use the exact same jar. A version mismatch causes registry sync errors (missing creeprchain:atm_block).

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Blockchain setup (tested on LINUX)

The blockchain runs on a separate Linux machine. All commands below are run on that machine inside the blockchain/ folder.

Step 1 — Install dependencies

cd blockchain
npm install

Step 2 — Start Hardhat node

scripts/start-local-chain.sh

This starts a local Ethereum node at 0.0.0.0:8545 (chain ID 31337). Leave this terminal open.

Step 3 — Deploy the contract

Open a second terminal on the same machine:

scripts/deploy-contract.sh

Output example:

Token deployed to: 0xAbCd1234...

Copy the contract address.

Step 4 — Configure blockchain.json

On the Minecraft server machine, edit config/creeprchain/blockchain.json:

{
  "rpcUrl": "http://192.168.0.108:8545",
  "chainId": 31337,
  "contractAddress": "0xAbCd1234...",
  "privateKey": "0xd345b787fa175fa22321746c8e0289ad88eac2de8c39ce67215c8b362af621e5"
}

• rpcUrl — IP of the Linux machine running the Hardhat node
• contractAddress — address printed by the deploy script
• privateKey — the Hardhat deployer account; this wallet signs mint/burn transactions on behalf of the server

Restart the Minecraft server. The log will show:

BlockchainService connected: rpc=http://192.168.0.108:8545 chainId=31337 contract=0x...

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MetaMask setup

1. Open MetaMask → Settings → Networks → Add network manually:
   • RPC URL: http://192.168.0.108:8545
   • Chain ID: 31337
   • Currency symbol: ETH
2. Add the token: MetaMask → Tokens → Import token → paste the contract address.
3. Note your MetaMask wallet address — you will use it with /linkwallet.

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In-game setup and test

/linkwallet 0xYourMetaMaskAddress

Place an ATM block (/give @p creeprchain:atm_block) and right-click it while holding a diamond (or another configured item). The tokens will appear in MetaMask.

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Commands

Command	Description
/linkwallet <address>	Bind your Minecraft account to an Ethereum wallet address
/balance	Show your token balance
/send <player> <amount>	Transfer tokens to another online player
/withdraw <amount>	Burn tokens (blockchain withdraw)
/withdraw <item> <count>	Burn tokens and receive Minecraft items

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Configuration

Config files live in config/creeprchain/ on the server. If absent, bundled defaults from src/main/resources/config/ are used.

economy.json — deposit and withdraw rates

{
  "depositRates": {
    "minecraft:diamond": 100,
    "minecraft:iron_ingot": 10,
    "minecraft:gold_ingot": 20
  },
  "withdrawRates": {
    "minecraft:diamond": 95,
    "minecraft:iron_ingot": 9,
    "minecraft:gold_ingot": 18
  },
  "maxDeposit": 10000,
  "maxWithdraw": 5000,
  "maxBalance": 100000
}

blockchain.json — connection to the Ethereum node

{
  "rpcUrl": "http://192.168.0.108:8545",
  "chainId": 31337,
  "contractAddress": "0x0000000000000000000000000000000000000000",
  "privateKey": ""
}

If privateKey is empty or contractAddress is zero, the mod runs in local-ledger mode (transactions stored only in SQLite, no blockchain interaction).

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License

MIT