Jelly Forest is a blockchain-enabled 2D runner game. The game features social sign in, multi-tiered upgrades (with higher tier requiring lower tier upgrades as inputs to build/mint), and cosmetic upgrades, all of which are stored in an embedded non-custodial smart contract wallet. There are no transaction signing popups or gas fee payment requirements emposed on players.
Download it with Google Play here! Learn why smart contract wallets here Learn what an embedded wallet is here This guide will walk you through how we built Jelly Forest and how you too can build your own web3 game using Sequence’s Unity SDK!

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1. Build a game loop

Step number one is building basic game loop. Don’t forget to think about your monetization strategy and how you’ll be using web3 elements first! For our game loop, we purchased the Infinite Runner Engine from the Unity Asset Store. Inside the asset, we found a demo scene JellyForest, which, with a few tweaks, we were able to get a functional build from on iOS and Android.

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2. Integrate social sign in and Sequence’s Embedded Wallet solution

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Configuration

  1. Install Sequence’s Unity SDK Using Package Manager
  2. Sign in to the Sequence Builder Console
  3. Create a Project For Your Game in the Builder Console
  4. Setup an Embedded Wallet in the Builder Console
  5. In your SequenceConfig scriptable object which you imported via the Samples menu in Package Manager during the installation stage, add your Google and Apple client ids which you added to the Builder as well as your Configuration Key under WaaSConfigKey
    • Don’t forget to put your Android and iOS client ids under their respective platforms!
  6. Add your Builder API Key from the Builder Console under Settings > API Access Keys - you want the prod key

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Social Sign In

  1. Create a basic scene where you will have your players login.
  2. Create a Canvas, attach a Canvas Scaler component and use the “Scale with Screen Size” UI Scale Mode. This will make it so that the LoginPanel (and any other UI elements under this Canvas) are scaled automatically when switching between build targets.
  3. Drag the LoginPanel prefab into your Scene Hierarchy under the Canvas. This can be found in the Project window under Packages > Sequence Embedded Wallet SDK > SequenceFrontend > Prefabs.
  4. Create a UI manager to call Open on the LoginPanel. See our implementation below:
private void Start()
{
    LoginPanel loginPanel = GetComponentInChildren<LoginPanel>();
    if (loginPanel == null)
    {
        Debug.LogError("LoginPanel not found!");
    }
    loginPanel.Open();
}
  1. Break the reference to the LoginPanel prefab in the Hierarchy so that you can edit it freely in the scene view
    1. Select the LoginPanel GameObject in the Hierarchy
    2. Right click the LoginPanel GameObject in the Hierarchy
    3. Prefab > Unpack Completely
  2. Customize the LoginPanel to fit your game’s theme
The LoginPanel will handle all of the social sign in logic for you. If you’re curious how it’s implemented, you can checkout the LoginPage and OpenIdAuthenticator implementations. The authentication works via the Open ID Connect Implicit Flow.

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Registering a Session with the Sequence API

Once social sign in is complete, you will automatically make a register session request with the Sequence WaaS (Wallet as a Service) APIs. Here’s how it works: When social sign in is complete, the OpenIdAuthenticator.SignedIn event is fired. This initiates the authorization process in SequenceLogin.ConnectToWaaS.

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Retrieving the User’s Wallet

In order to retrieve the wallet, you’ll need to subscribe to the SequenceWallet.OnWalletCreated event. 
SequenceWallet.OnWalletCreated += OnWalletCreatedHandler;
public void OnWalletCreatedHandler(SequenceWallet wallet) {
  // Do something
}
We highly recommend you import SequenceConnector via the “Useful Scripts” under Samples in the Package Manager page for the “Sequence Embedded Wallet SDK”. By default, it contains a lot of helpful starting code and acts as a useful interface to communicate with the SDK. We used it quite heavily in our integration with JellyForest. In JellyForest, we also created a LevelLoader MonoBehaviour that loads the next scene when the SequenceWallet.OnWalletCreated event is fired. 
private void Awake()
{
    SequenceWallet.OnWalletCreated += OnWalletCreated;
}

private void OnWalletCreated(SequenceWallet wallet)
{
    SceneManager.LoadScene("MenuScene");
}
For more information on how auth in Sequence’s Embedded Wallet solution works, please see our docs and blog post.

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3. Deploy a Collectibles Contract

Now that our players can sign in and get a wallet, let’s add some collectibles! We highly recommend using an ERC1155 contract. They are a flexibly token standard that are well suited for games. You can easily deploy our audited ERC1155 implementation via the Builder Console like this:
This is what we did for Jelly Forest. Once you’ve deployed your smart contract, don’t forget to add your contract address as a Sponsored Address on the “Gas Sponsoring” page on the Builder Console! This will make it so that your users have their gas fees automatically sponsored using your compute credits when interacting with your game’s smart contracts.

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4. Deploy a Remote Minter

By default, ERC1155 contracts deployed via the Builder Console require callers to have the appropriate permissions in order to mint a token. While this may seem like a nuisance at first glance, this is a good thing! Without this, anyone could call the mint method on your contract and give themselves infinite in-game items! You’ll want to deploy a server with a Sequence wallet (or other) and give it minting permissions in the builder.

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How We Did It in Jelly Forest

In Jelly Forest, all the coins you collect during gameplay are minted as ERC1155 tokens. Here’s how we did it:
  1. Sign up for Cloudflare - this is how we host the minting service code; please feel free to use any other method you prefer
  2. Open terminal or other command line
  3. git clone https://github.com/0xsequence-demos/cloudflare-worker-sequence-relayer.git then cd cloudflare-worker-sequence-relayer
  4. git checkout permissionedMinter
  5. pnpm install - to install dependancies
  6. Install wrangler
pnpm install wrangler --save-dev
alias wrangler='./node_modules/.bin/wrangler'
and login 
wrangler login
  1. Open wrangler.toml
    1. Give your server a name by changing the name string
    2. Create a new EOA wallet and export the private key. Any EOA wallet is fine. Metamask can be used to easily setup a wallet and export the private key. Please be very careful with the private key and don’t store it in plain text on your computer or commit it to version control! Set this under PKEY
    3. Set the CONTRACT_ADDRESS
    4. Set the PROJECT_ACCESS_KEY - this is your prod API key from the Builder Console you retrieved earlier when setting up the SequenceConfig scriptable object
    5. Set the CHAIN_HANDLE - if you’re not sure what this is, you can see the CHAIN_HANDLE for each respective network on the Node Gateway page of the Builder Console.
  2. pnpm dev - this will deploy the server locally. You should see which localhost it is deployed to in the command line
  3. Open another command line window
  4. curl http://localhost:8787 - substitute whichever localhost you are given. This will ping the server.
  5. In the command line where the localhost server is running, you should see that the minter’s wallet address has been logged
  6. Grant this address minting permissions in the Builder Console
    1. Find the contract under Contracts and click to open it
    2. Click Write Contract
    3. Expand grantRole
    4. Under role enter 0x9f2df0fed2c77648de5860a4cc508cd0818c85b8b8a1ab4ceeef8d981c8956a6 - this is the Keccak-256 hash of MINTER_ROLE
    5. Under account paste the minter’s wallet address
  7. wrangler deploy - this will deploy the code to a Cloudflare Worker and give you a minting URL
Great! Now, when we send a POST request to our server with a body defined in C#, where the proof is generated by the client sending the minting request. In the Unity SDK this is implemented by the MintingRequestProver.

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5. Mint In-game Tokens to the Player’s Inventory

Now that we have our permissioned minter server setup, we need to get the client side (the Made With Unity app) hooked up so that we can start giving our players tokens through gameplay. We can send a request to the permissioned minter using the Unity SDK by calling the PermissionedMinter.MintToken method. In Jelly Forest, as the player runs through the level they collect a lot of coins, these are all ERC1155 tokens. There are still a few challenges we need to solve for in order to provide our players with a great UX.
  1. How do you read the chain to know what tokens/entitlements the user has in their inventory?
  2. Blockchain transactions, while fast on some chains like Arbitrum, are not instant. Collecting a coin (or some other item) then needing to wait a few seconds before it shows up in your inventory in the game is, in general, not a great end-user experience.
  3. At first glance, you may be tempted to submit a transaction anytime a user earns a token via your game. However, in most games, especially games like Jelly Forest where players collect a lot of coins (tokens), this will end up submitting a ton of transactions and will cost you a fortune in gas fees!
Let’s see how we solved for all of these problems in Jelly Forest using the Unity SDK!

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1. Reading the Chain

Reading the tokens in a given user’s wallet is a complicated process that is made much easier using Sequence’s Indexer which the Unity SDK implements. Here’s a code snippet from Jelly Forest where we use the Indexer to read all the tokens in a player’s wallet from our game’s ERC1155 contract. 
private Dictionary<BigInteger, TokenBalance> _tokenBalances = new Dictionary<BigInteger, TokenBalance>();
private async Task GetTokenBalances(Page page = null)
{
    if (page == null)
    {
        page = new Page();
    }
    GetTokenBalancesReturn balances = await _indexer.GetTokenBalances(new GetTokenBalancesArgs(_userAddress, SequenceConnector.ContractAddress, false, page));
    int uniqueTokens = balances.balances.Length;
    for (int i = 0; i < uniqueTokens; i++)
    {
        _tokenBalances[balances.balances[i].tokenID] = balances.balances[i];
    }
    if (balances.page.more)
    {
        await GetTokenBalances(balances.page);
    }
}

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2. Building a Cache

Since blockchain transactions are not instant but we want to provide our user with instant feedback, we’ll make use of a simple in-memory cache. When we first receive our SequenceWallet in Jelly Forest, SequenceConnector, which we used as our primary interface for communicating with the Sequence SDK in our game, creates an Inventory. 
private void OnWalletCreated(SequenceWallet wallet)
{
    Wallet = wallet;
    Wallet.OnSendTransactionComplete += OnSendTransactionCompleteHandler;
    Wallet.OnSendTransactionFailed += OnSendTransactionFailedHandler;
    Wallet.OnSignMessageComplete += OnSignMessageCompleteHandler;
    Wallet.OnDeployContractComplete += OnDeployContractCompleteHandler;
    Wallet.OnDeployContractFailed += OnDeployContractFailedHandler;
    Wallet.OnDropSessionComplete += OnDropSessionCompleteHandler;
    Wallet.OnSessionsFound += OnSessionsFoundHandler;

    Inventory = new Inventory(Indexer, Wallet.GetWalletAddress(), ItemCatalogue); 

    _transactionQueuer.Setup(Wallet, Chain);
    _permissionedMinterTransactionQueuer.Setup(Wallet, Chain, "https://sequence-relayer-jelly-forest2.0xsequence.workers.dev/", ContractAddress);
}
The Inventory is used as a simple cache in our game. When first created, and when prompted, we use the Indexer to fetch all the tokens in the users wallet. From here, whenever the user earns a token, we update our cache (Inventory) and the on-chain data. Read the full Inventory implementation here

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3. Using a Transaction Queue

Sequence’s Unity SDK provides a very flexible transaction queueing system. In Jelly Forest, we attached a PermissionedMinterTransactionQueuer MonoBehaviour to our SequenceConnector GameObject and grab a reference to it in Awake. PermissionedMinterTransactionQueuer Once this is setup, all we need to do when a token is collected is call “mint token”. 
public class CollectibleToken : Coin
{
    protected override void ObjectPicked()
    {
        base.ObjectPicked();
        if (SequenceConnector.Instance == null || SequenceConnector.Instance.Wallet == null)
        {
            Debug.LogWarning("No minting will happen. Make sure SequenceConnector is in the scene and user is logged in.");
            return;
        }
        SequenceConnector.Instance.MintFungibleToken(); 
    }
}
This will update our Inventory and add a mint transaction to the PermissionedMinterTransactionQueuer’s queue. The PermissionedMinterTransactionQueuer will automatically merge transactions together when possible so that you spend the least amount of money on gas fees as possible. In Jelly Forest, we’ve configured our transaction queuer to submit transactions every time the player has a game over, but no sooner than every 30 seconds.

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How Do You Determine How Often to Submit Your Transactions?

With our Unity SDK, this becomes more of a game design question than anything else. Our TransactionQueuers can be configured to submit transactions automatically every X seconds, when promted (via function call) but no sooner than every Y seconds, or when prompted overriding any minimum time threshhold configured (Y seconds). Here are some things to consider when determining how to configure your transaction queuers:
  • The more frequently you submit transactions, the more gas fees you’ll pay. Of course, the EVM-compatible blockchain you select will heavily influence the number and complexity of transactions you can submit before costs become prohibitive.
  • The less often you submit tranactions, the further out of sync your game state (cache) will become with the information on-chain. If a transaction were to fail, you will need a way to recover from this without hurting your players’ experience of the game.
As an example from Jelly Forest: we felt that the Shops’ transactions were of high importance to the end user. We didn’t want to risk a user thinking they had an upgrade/hat and then having the transaction fail and needing to either revoke the upgrade/hat or mint an extra one that the player may not have legitemately earned. So, we made it so that the user waits on the Shop pages until the purchase transaction (and all other transaction in the TransactionQueuers) have succeeded. 
public async Task Buy()
{
    if (Status != ItemStatus.Available)
    {
        return;
    }

    if (SequenceConnector.Instance == null)
    {
        string error = "SequenceConnector not found. User has not logged in";
        Debug.LogError($"Failed to purchase shop item: {error}");
        OnFailedToPurchaseShopItem?.Invoke($"Failed to purchase shop item: {error}");
        return;

    SequenceConnector.Instance.AddToTransactionQueue(new PurchaseShopItemQueueableTransaction(this));
    TransactionReturn result = await SequenceConnector.Instance.SubmitQueuedTransactions(true, false); 
    if (result is SuccessfulTransactionReturn successfulTransactionReturn)
    {
        BurnTokensFromInventory();
        MintTokenInInventory()
        if (string.IsNullOrWhiteSpace(successfulTransactionReturn.txHash))
        {
            GetTransactionReceipt(successfulTransactionReturn);
        }
    }
    else if (result is FailedTransactionReturn failed)
    {
        string error = $"Transaction failed: {failed.error}";
        Debug.LogError(error);
        OnFailedToPurchaseShopItem?.Invoke($"Failed to purchase shop item: {error}");
    }
    else
    {
        throw new Exception("Unexpected transaction result type");
    }
}

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6. Burn In-game Tokens in Exchange for Others

In Jelly Forest, you can purchase powerups and cosmetics by burning coins and (sometimes) lower tier powerups. To enable and enforce this mechanic, we deployed a simple BurnToMint smart contract. This contract allows you to specify minting requirements (required token ids and associated amounts) for a given token id. When it receives a batch of ERC1155 tokens and the sender specifies the token id they want to mint in the data parameter, the contract will check if it received the required amount of each token id; if this passes, the contract burns the tokens and mints the requested token id to the sender (user); otherwise, the transaction fails and reverts. We’ve given this contract minting permissions for our game contract in the Builder Console:
  1. Find the contract under Contracts and click to open it
  2. Click Write Contract
  3. Expand grantRole
  4. Under role enter 0x9f2df0fed2c77648de5860a4cc508cd0818c85b8b8a1ab4ceeef8d981c8956a6 - this is the Keccak-256 hash of MINTER_ROLE
  5. Under account paste the minter’s wallet address
:::danger Warning: the BurnToMint smart contract shared above has not been audited by a third party. Re-use with caution! ::: When a user purchases an upgrade or cosmetic from the shop, we send a transaction to the BurnToMint smart contract by adding a PurchaseShopItemQueueableTransaction to our SequenceWalletTransactionQueuer in our SequenceConnector. 
SequenceConnector.Instance.AddToTransactionQueue(new PurchaseShopItemQueueableTransaction(this));

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7. Building the Shop Pages and Setting the Minting Requirements

When building the Shop Pages and setting the prices/minting requirements for the different upgrades and hats in Jelly Forest, we opted to define ShopItems using Scriptable Objects because they are easy to tweak and visualize since they can be serialized in the Inspector. These scriptable objects are also how we define what each Item is and associate them with a token id. However, it quickly became a pain (not to mention a potential source for bugs) to keep the minting requirements defined in the Scriptable Objects in sync with the minting requirements defined in our BurnToMint contract on-chain. We created an editor extension for our ShopItem scriptable objects adding a button that, when pressed, will check if the minting requirements defined on-chain match what is defined in the scriptable object; if they differ, it will send a transaction to update the minting requirements in the BurnToMint contract on-chain to match the scriptable object. The transaction is submitted via an EOA wallet created from a private key stored as an environment variable on one of our developer’s machines. This EOA wallet is the owner of this contract. In fact, our Shop Pages actually query the smart contract every 60 seconds (and every time they open) for changes in minting requirements, updating their UI accordingly. This allows us to make live patches to our game’s economy without requiring an update! Click on the video below
See the ShopItemEditorExtension implementation here.

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8. Leverage Purchased Items In-game

Ok great, our players can log in, get a wallet, earn tokens, and buy things with their tokens, all that’s left is to give your players a reason to want to buy stuff in the first place. In other words, it’s time to go work your game developer magic and build some awesome powerups and cosmetics! All you have to do to bring your tokens into your game is check if the user owns enough of the given token id and apply the token’s effect. In Jelly Forest, we defined a few different PowerUpTypes and assign each Item a PowerUpType and tier. Then we query our Inventory to find the best power up of each type that the player owns.