Detailed explanation of Starknet game engine Dojo: the starting point of chain games

Original: Dojo on Starknet: Game On!

Translation and proofreading: "Starknet Chinese Community"

Starknet's first provable game engine

Featured Quick Facts

• Dojo is a provably on-chain game engine that empowers game ownership, interoperability, and scalability.
• Dojo runs on Starknet, providing game creators with a software framework that helps game developers create high-quality, seamless, and fast games.
• Dojo enhances game development by enabling fast and low-cost transactions, which is required for production-grade encrypted games.
• Components such as ECS, Sozo, Torii, and Katana help with game development and deployment.
• Future Dojo enhancements include L3 game research, optimistic updates, client proofs, and cross-chain transfers.
• Starknet full-chain games powered by Dojo are increasing, such as "Dope Wars", "Influence", "Realms" and "CafeCosmos", marking the growth trend of on-chain games.

Blockchain games did not live up to expectations. Scale limitations and high costs make most on-chain games only able to tokenize in-game assets. But with low-cost and fast transactions enabled by Starknet and the new Dojo crypto game engine, owning in-game assets and proving game logic on-chain is becoming a reality.

Worth $245 billion by 2023, the global gaming market is one of the largest segments in the global entertainment industry. Blockchain gaming promises limitless interoperability, offering an even more exciting entry into the gaming world than the current scene. Just as multiplayer games add new possibilities to the gaming ecosystem, on-chain games can become more interesting and valuable.

But this promise has to face the reality of blockchain "transactions are expensive and slow". These are two problems that should be avoided in the game. Because of this, creating successful on-chain games is nearly impossible.

But with the maturity of the "validity proof rollup" technology, the promise of on-chain games has finally been fulfilled.

In this article, we will see how the high TPS provided by Starknet can fulfill the promise of on-chain gaming. We'll also learn how Dojo, the first community-built verifiable game engine, uses Starknet to empower creators. Finally, the future of Dojo and the fun it brings to blockchain gaming will be explored.

Crypto Games

When we talk about blockchain games, the two most popular ideas blockchain supports are ownership and interoperability of in-game assets.

In-game asset ownership means that game assets belong to wallets owned by users. In other words, game assets do not belong to the game developer, nor do they belong to an email account, which may be stored on a centralized server, and the game developer can delete it remotely. In blockchain games, the assets you create or earn truly belong to you.

Once these assets are yours, games can achieve interoperability. Through interoperability, characters and assets in one game can be transferred to a different game or world. If you've put hundreds of hours into a game but decide you're no longer playing it, you can transfer those hard-earned assets to a new game of your choice.

In order to realize these two concepts, games must be built on-chain. This means that all in-game assets, all actions taken by players, and any other state changes must be made on the blockchain as transactions (each action can be done individually, or as an aggregated transaction that is pushed periodically). On a fairly decentralized blockchain, a single transaction can cost anywhere from a few cents to hundreds of dollars (in times of network congestion), and take a few minutes or longer. Obviously, this makes it extremely expensive, slow, and impractical to operate large gaming infrastructures on such platforms.

Starknet and Low Cost Computing

But with the emergence of "validity proof rollup" such as Starknet, all this is changing.

Starknet is a "validity proof rollup" L 2 (commonly known as ZK-Rollup) developed by StarkWare. It uses an encryption system called STARK to drastically reduce computation and storage costs. (To learn more about cryptographic proofs on Starknet, check out this article.)

Starknet (and Cairo, Starknet's smart contract language) allow dApps to process high TPS at a fraction of the cost while leveraging the security of Ethereum. These low-cost and fast transactions are exactly what is required to realize the promise of blockchain gaming. These games are now fully on-chain, fast and affordable.

But even with on-chain capabilities, a second key building block is needed for blockchain games to thrive: a provable game engine.

What is a Game Engine

A game engine is a software framework that enables beautiful settings, snappy gameplay, and realistic character behavior in your favorite games. Game engines typically include libraries and supporting programs that provide developers with a framework so they don't have to recreate each game's basic systems (such as physics, graphics, and game mechanics) from scratch. Game engines can also include audio and video processing, rendering of 3D effects, and AI capabilities.

A game engine is the foundation upon which games are built.

Most of the games we love to play benefit from two of the most popular game engines in the world: Unity and Unreal Engine. Unreal Engine, developed by Epic Games, has been used in popular titles such as Fortnite, Street Fighter V, and the Gears of War series. Unity, another important player in the game engine industry, has given life to games such as "Hearthstone", "Ori and the Dark Forest" and "Pokémon Go".

As Starknet fulfills the promise of crypto gaming, a slew of projects have started building games on Starknet. But there is still a lack of encrypted game engines that allow developers to build games without writing custom code for basic physics, logic, and game mechanics, and keep all of them on-chain.

Dojo is the first provably game engine

Dojo is that crypto game engine, a community-built, provable game engine and toolchain for building on-chain games and autonomous worlds. Making the promise of crypto gaming a reality.

The number of games using Dojo on Starknet is growing rapidly. Some of the most popular include:

Influence — a grand strategy MMO set in a distant asteroid field with an open economy for players. Users can purchase NFTs to explore and develop asteroids. All asteroids are in the same world, and players interact with each other.

Realms — a strategy game featuring 8,000 land maps with specific names, shapes, sizes and geographic characteristics, providing users (owners of the land) with on-chain utilities such as resource generation and tradable housing base components, Economic trade can be carried out between players.

"CafeCosmos" - a full-chain land game where users must efficiently manage resources, including collecting resources, farming and raising animals, crafting utensils and furniture, trading assets, and more.

Dojo components

The Dojo ecosystem consists of the following components:

ECS (Entity Component System) written in Cairo

Sozo Migration Planner

Torii Network and Index Stack

Katana RPC Development Network

Let's explain one by one.

The ESC system is a design pattern in game development that makes code easier to maintain. The ESC system allows game developers to give game objects (entities) unique functions (components), and allows the entire scene to function as an integrated system. This makes it possible to build complex and dynamic games on the blockchain. While supporting multiple game mechanisms and interactions, it also takes advantage of the transparency and decentralization of blockchain technology.

Also, since Dojo is written in Cairo, it maximizes the efficiency of the code that needs to be proven. (See this post for more on Cairo complexity and provable implications.)

Sozo is a toolchain dedicated to building and migrating plans. In short, Sozo can be used to deploy developed games to Starknet. An example of deploying a game "world" on-chain is done with a simple sozo migrate command. Sozo is only available as a command line interface (CLI) tool, a graphical user interface is still under development.

Torii is the comprehensive indexing and networking layer in the Dojo world. The Torii system is built on Dojo and as such is designed to retrieve arbitrary events deployed in on-chain game worlds. Torii can systematically organize the Dojo world state, making the client's data query more convenient and efficient. Given that games contain many state changes, each click is assumed to be a state change, so an efficient retrieval system becomes an important feature on the Dojo stack. Queryable with GraphQL on Torii.

Katana is a high-speed local Starknet node used to support Dojo local development. Katana allows developers to test applications on devnet for efficient local development. Developers can use the Katana network to test sending transactions in the game. Katana can provide a convenient RPC method to change the network configuration according to the needs (for example, change the block time or allow 0 gas transactions, etc.). Additionally, Katana supports v0.3.0 of the Starknet JSON-RPC specification (latest version as of June 2023). Native Starknet JSON calls, such as starknet_getTransactionReceipt, starknet_getStorageAt can be used in Katana.

Looking to the future of Dojo and crypto gaming

The Dojo community will continue to research and build to promote the development of encrypted games. In addition to improving existing components, the developers are working on the following:

• L3 for exclusive games
• optimistic update
• Client certificate
• Cross-chain asset transfer

Let’s explore the significance of each of these items to the entire chain of games.

L3 for games — Dojo is investigating the feasibility of developing L3 games on Starknet. This means deploying a separate chain on Starknet that periodically attests to the execution of its transactions and submits the proofs to Starknet (L2). Starknet aggregates this proof with other transactions on the network and submits the proof to Ethereum L1 for verification. This solution can increase the scalability of the game several times. (As an extra step, consider what would happen if a new one-time-use layer was built on top of the game layer every time the player tried a level in the game.)

Optimistic update — how many times have we silently waited for the "transaction in progress..." text in our wallet to turn green and show the transaction "verified"? The answer is: often. If every step a player takes in the game is sent as a separate transaction, the player will waste a lot of time waiting for the transaction to be accepted.

The optimistic update (which Dojo is working on adding as an extra feature to its stack) gets rid of this problem by running transactions optimistically on the client side (in the browser itself), allowing players to keep playing. If for some reason the outcome of the transaction differs from running it in the browser, the game will adjust.

Client-side proofs — In addition to optimistic updates running on the client side, Dojo is also exploring the possibility of client-side proofs of partially on-chain transactions. This will allow games built on Dojo to effectively hide certain inputs passed by the user, since zero-knowledge proofs (ZK proofs) of receiving these inputs can be created on the client side. In turn, this zero-knowledge proof can be sent to an on-chain orderer, which executes the rest of the transaction.

Proof of storage — Proof of storage is the use of cryptography to store blockchain information to achieve cross-chain information sharing. Similar to oracles, proofs of storage provide proof of the authenticity of information. But unlike oracles, Proof-of-Storage does not require trusting a third party to prove. With Proof of Storage, trust is built into storage. Proof of Storage can also prove the validity of the state of other chains or other layers built on top of Ethereum.

Dojo is working with the Herodotus team to implement Proof of Storage in Dojo, eliminating the need for cross-chain asset transfers. Ownership of assets from different chains can be proven through proof of storage, and users can use their assets in different games on different chains or on different layers. (See the section on building a standalone L3 game on Starknet discussed above.)

Conclusion

Dojo is the world's first provable game engine, other implementations benefit from the availability of Starknet and Cairo. With a provable game engine like Dojo, true on-chain crypto games are starting to emerge. The promise of "interoperability and ownership" is gradually being realized.