Axelar was excited to participate in the recent HDGames Hackathon, powered by H.E.R. DAO, Womenhack and Aves Lair. This two-day hybrid hackathon took place online and IRL in Los Angeles, and saw over 135 hackers participate to compete for a pool of over $100,000 in grants and prizes. The hackathon was focused on game development and helped match participants with fellow builders, mentors and investors to bring their projects to life and help them continue building after the hackathon ended.

Axelar hosted a bounty where hackers who used Axelar General Message Passing (GMP) in cross-chain applications competed for a prize pool of $5,000. We saw some incredible and innovative projects that integrated Axelar into their dApps to interact with contracts across multiple chains using GMP. Here are the top two submissions from the HDGames Hackathon:

1st Place: BuildIt

Prize: 3,000 USDC

BuildIt is a metaverse project developed for the hackathon. BuildIt allows users to:

• Own virtual land within a map represented as ERC-721 tokens.
• Place items on their owned land, such as buildings, roads and other structures, represented as ERC-1155 tokens.
• Sell their land to other users, transferring ownership and associated items.
• Connect their wallets (e.g., MetaMask, Coinbase, WalletConnect) to interact with the metaverse.

All interactions within the metaverse are secured by smart contracts.

When a user connects their wallet, the game fetches data from the smart contracts and highlights the portion of the map that the user owns. Users can then click the "Edit" button to place or remove items on their land. They have the option to cancel or confirm the changes, which updates the items in the appropriate locations. Smart contract checks ensure that users can only interact with the land they own.

In addition, BuildIt includes a marketplace where users can sell their land through direct listings or auctions. Chainlink automation can be utilized for auction listings. If the chain supports Chainlink price feeds, the land can be sold for USD. The marketplace provides an easy and secure way for users to trade their land.

BuildIt was built using the following technologies and tools:

• Unity: The game was developed using Unity and built for WebGL.
• Smart contracts: Four smart contracts were developed using Foundry and Hardhat:
  • Map contract: Responsible for the lands in the map, implemented as an ERC-721 contract.
  • Utils contract: Represents the items that can be placed on the land, implemented as an ERC-1155 contract.
  • Faucet contract: Allows users to obtain items for free initially. It is funded to provide items for judges and other participants.
  • Marketplace contract: Facilitates land sales through direct listings and auctions.
• Map size: The map size is determined in the smart contract, allowing the deployment of multiple maps with different sizes. The current deployment consists of a map 15 by 15 tiles in size, where each land is a 5-by-5 tile.
• Item minting: Three items are minted in the Utils contract: road, house and special item.
• Wallet integration: Users can connect their wallets, such as MetaMask, Coinbase and WalletConnect, to interact with the metaverse.
• Gasless transactions: All smart contracts implement ERC2771Context, enabling users to perform gasless transactions when the relayer is funded.

Learn more about BuildIt here: https://dorahacks.io/buidl/6575

Demo: https://www.youtube.com/watch?v=xnALT8uTKDc

GitHub: https://github.com/Ahmed-Aghadi/BuildIt-cross-chain

2nd Place: Fir3wall

Prize: 1,500 USDC

Fir3wall’s vision is to add a security layer on intra- and cross-chain transfer of assets.

These days we hear a lot of cases about tokens getting transferred to the wrong account. This may happen due to negligence or some kind of malware that changes the address while we are transferring tokens. This problem is increasing day by day. Once the funds are transferred, the transaction cannot be reversed.

Therefore, it is vital to have middleware which can be used to make transactions secure. Fir3wall aims to provide users with a seamless solution to transfer ERC-20 tokens between accounts across different blockchains while maintaining control over their funds.

Fir3wall is an added security layer designed to enhance the safety of cross-chain asset transfer. It supports transfer of ERC-20 tokens from one network to another. If tokens are delivered to the wrong address, users may quickly undo transactions. It functions by using a smart contract to store funds until the designated recipient claims them. The sender has the option to reverse the transaction and get their tokens back if the recipient doesn't pick up the tokens or if they realize they sent tokens to the wrong or unanticipated address. The receiver can claim the funds and bridge them to another network by paying the desired gas fees and safely completing the bridging of tokens from one chain to another.

Axelarscan testnet: https://testnet.axelarscan.io/gmp/0x3e38c27c76e4eb2fb96d79454caff21fd07882ebeb382ff9fe1db3ebd2a51b04:48

More about Fir3wall: https://dorahacks.io/buidl/6318

GitHub: https://github.com/shivanshxyz/Fir3wall