Application of zk-SNARKs in Full Chain Games: Taking PopCraft as an Example

PopCraft is a fully on-chain elimination game where players need to clear all elements on the board within 4 minutes to earn token rewards. However, since the game runs entirely on-chain, each player action requires interaction with the blockchain, leading to noticeable latency issues. The block time on Ethereum's Layer 2 networks is typically 2 seconds, which means players must wait at least 2 seconds for each action to complete, significantly affecting the gaming experience.

To solve this problem, we consider using zk-SNARKs ( ZKP ) technology to reduce the frequency of interactions with the blockchain during the game process. Ideally, the game process does not need to be on-chain, but still ensures no cheating risk. The specific idea is: each player's action generates a ZKP, and the ZKP of the next step is based on the previous one, forming a self-contained ZKP similar to a blockchain structure. At the end of the game, only the ZKP of the last action needs to be sent on-chain for verification by the smart contract.

However, this plan faces many challenges during the implementation process:

1. Cheating prevention in the game process and results: generating ZKP alone is insufficient to prevent cheating; the entire game process also needs to be verified.

2. The technical challenges of gradually generating ZKP: each step of the ZKP relies on the previous step, and how to verify its coherence and correctness on-chain is a complex issue.

3. Handling of public game data: The game data of PopCraft is already public, so using ZKP for information hiding seems unnecessary. But if ZKP is not used, how can game data be securely stored and verified on the smart contract side?

4. Processing the consumption of game items (Token): When players use items to eliminate isolated elements, it involves the transfer of Tokens. How to handle this process within the ZKP system while ensuring real-time performance and accuracy is a challenge.

5. The data hiding feature of ZKP: In scenarios like PopCraft where there is no need to hide game data, using ZKP actually increases the difficulty of data acquisition and the complexity of implementation.

After in-depth analysis, we have drawn the following conclusions:

For games like PopCraft, the key is to find a method that ensures no cheating is possible at every step from the beginning to the end of the game, while only needing to verify the correct result on the chain at the end. However, it seems that ZKP is currently difficult to completely solve this problem.

Based on existing research, ZKP is mainly applicable in the gaming field in two scenarios:

1. Information hiding in incomplete information game types, such as Dark Forest, Texas Hold'em, etc.

2. Proof of the results of single-step games, such as lotteries, number guessing, and other simple games.

Given the complexity of zk-SNARKs technology, the analysis and conclusions in this article may have certain limitations. We welcome further insights and guidance from experts in this field.