Rollbacks in Decentralized Games
Chain reorganization (reorg) is a wonderful property unique to blockchains which allows clients to trustlessly reach consensus with probablistic finality; however, chain reorgs in decentralized games is a bug, not a feature.
Recently having some free time, I’ve been helping Nine Chronicles (NC) by participating in their CBT.
Nine Chronicles is a game developed by Planetarium that showcases their Libplanet library, a “blockchain core in C#/.NET for persistent peer-to-peer online games.”
They imagine a world where:
- Games run on clients running the same software; no servers required to play.
- Fork the codebase without permission for maximum moddability if you don’t like a game or see improvements which can be made.
- Development costs for games are secured through new revenue models.
In line with this vision, there are 0 servers running NC and the whole game runs on clients that reach consensus through Proof-of-Work. PoW provides probablistic finality which means that as a block sinks deeper into the chain, the harder it becomes to revoke a transaction in that block.
I’ve been following the game from day one, participated in its alpha, and found reorgs happening regularly. Understanding Nakamoto consensus and that we’re in beta, I’ve given up fretting and accepted reorgs as an annoyance all decentralized games will have for the time being—until this week.
This week, a 700 block deep reorg took place following a client update. I’ve wondered how it would be to update crypto games and haven’t realized how tricky it really can be. Long story short, I felt cheated and frustrated.
Numerous players have complained of having lost precious time and energy, levels, and in-game items. However, 700 blocks of work gone for all the testers struck a nerve. Throw in the added “benefit” of permanent loss with absolutely no way of getting anything back. Because it’s decentralized, there’s no admin to cry and complain to nor can they take any measures such as a rollback.
I believe this reorg problem can eventually be solved through clever engineering, whereas there’s no escaping the fact that as a crypto game gains traction, a malicious 51% attack on a valuable chain is a clear and present danger. For games using general purpose blockchains such as Ethereum this isn’t much of an issue. On the other hand, games built on game-specific blockchains using probablistic or economic finality are vulnerable at all times.
A game developer friend told me of several server rollbacks during the early days of Maplestory. Apparently, the hardest part post-rollback was not angry users leaving the game but rather recompensing users for their lost time and energy. Nexon had to navigate through financial laws across varying jurisdictions regarding digital items.
It’s clear crypto solves complexities of financial laws across jurisdictions. However, crypto doesn’t abate angry users—it grants game developers less power to “right wrongs.”
Consider for a moment a case where a dissatisfied user sues a game company over a reorg and permanent loss of in-game items. Although the company can sidestep legal ramifications citing blockchain and its censorship-resistance, the same censorship-resistance turns players off.
I was surprised to find that losing levels and items which I had farmed before this reorg did not upset me. I was upset by lost Nine Chronicles Gold ($NCG), a in-game currency in NC rewarded either for mining or for selling items in their P2P marketplace.
NC CBT does not offer ways of earning $NCG other than upgrading items and selling them on the market. As there are no NPC shopkeeper, I was always strapped for cash. Before switching mining on a week ago, NC was an idle MMORPG. After starting to mining this week, NC suddenly morphed into a trade simulation game.
The reorg presented an immutable, choose-your-own-adventure, deja vu experience where users started from a certain snapshot in the past without levels, items, and $NCG earned after the snapshot. I instinctively knew the computing power and the token rewards from mining were never coming back while understanding the levels and items could be farmed again. Being fully immersed in the economic aspect of a game was new.
During the bull market of 2017, in order to explain the barrage of layer 1 blockchains on the ICO bandwagon there was a sentiment that depending on the nature of the dapp, teams would need to select the appropriate blockchain architecture to build on. This reorg brought to light a fact that it would be wise for teams to select an appropriate blockchain depending on the type of game they wish to create.
The $NFT madness happening on NBA Top Shot makes sense to be on Flow—their competitive edge is their partnership with the NBA and monopoly over NBA-related IP and content. Without the content matching the technology, crypto games are more liable than its centralized counterparts.
All that being said, I can’t wait to see what video gaming creativity will be unleashed on what blockchain—forks, reorgs, and all.