This sci-fi blockchain game could help create a metaverse that no one owns

Start exploring in Dark Forest, and you quickly realize just how much you don't know.

The universe is vast, and most of it is shrouded in darkness. Your mission, should you choose to accept it, is to venture into the unknown, avoid being destroyed by opposing players who may be lurking in the dark, and build an empire of the planets you discover and can make your own.

But while the video game seemingly looks and plays much like other online strategy games, under the hood it's a very different story.

That's because it doesn't rely on the servers running popular online strategy games like Eve Online and World of Warcraft. Instead, Dark Forest runs completely on a blockchain, in a way that means no one is in control of how it plays out.

Its early success doesn't just reflect a fun way of making games that work in an entirely different way. It also helps prove that blockchains can be used for far more interesting and complex applications than just moving digital money around, something some blockchain boosters have been saying since the technology first emerged.

In fact, the game's most die-hard fans believe that what makes it so cool is something even more profound-something that hints at the future of our shared digital realms. And that includes the possibility of a metaverse that isn't owned by Meta or another big tech company but runs in a decentralized way, between its users.

How it was built

Dark Forest began as an idea in the mind of the pseudonymous Gubsheep (maintaining pseudonymity is not uncommon among figures in the crypto world), who describes it as a massively multiplayer strategy game that takes place in an infinite, procedurally generated universe."

The game is partly inspired by the science fiction novel The Dark Forest, by Cixin Liu. Gubsheep says he was so enthralled by the book that he read it in just one sitting, in a bookstore cafe. One theme he found particularly compelling involves the dilemma our civilization would face if it were to discover another civilization in the universe. We wouldn't know whether it posed an existential threat, says Gubsheep, but one view is that to ensure our own survival we should assume so and make no contact.

Gubsheep happened to read The Dark Forest just a few days after he had attended a conference focused on an emerging class of cryptographic tools called zero-knowledge proofs. Using this advanced cryptography, it's possible to prove that a statement is true without revealing anything else about it. Imagine, for instance, proving your citizenship without revealing any of the other information in your passport.

As he walked back to his apartment from the bookstore, fresh ideas inspired by The Dark Forest started to combine with others sparked by what he had just learned.

The idea behind zero-knowledge proofs dates back to the 1980s, but some of the first practical applications have appeared recently in blockchain systems. The most prominent example is Zcash, a Bitcoin-like cryptocurrency that uses a class of zero-knowledge proofs called zk-SNARKs-the same kind Dark Forest uses-to hide transaction data so that users can deal anonymously, almost as if they were using a digital form of cash.

Gubsheep began to imagine a cryptographic Dark Forest" in which opposing players would be like civilizations tiptoeing" through a universe filled with potentially hostile counterparts-hidden from view thanks to zero-knowledge proofs. When he got home, he stayed up all night sketching out the idea. Shortly thereafter, he convinced two friends to help him build it.

Eventually, Dark Forest's creators decided that to make it work they'd need to use a blockchain. They wanted to build the game in a way that would allow everyone to be able to check that the mathematical protocol underlying the game is being followed correctly," says Gubsheep. He acknowledges that it would have been technically possible to write the game in a traditional server so that its entire history would be viewable, including every zero-knowledge proof-but at that point you're basically starting to build a blockchain."

They knew it was a pie-in-the-sky" idea. Blockchains are slow and expensive to use-far from ideal infrastructure for a game that must keep track of many interconnected systems and a vast number of player moves. Despite all the initial hype around a wide range of non-finance uses for blockchains, the popular perception now is that using blockchains makes sense only for simpler, finance-related applications.

Proof of concepts

Gubsheep and his friends achieved what they set out to do: make a cool, sci-fi-inspired game using cutting-edge cryptography. What they built, however, has hinted at new possibilities they didn't fully anticipate.

Dark Forest is the most complicated blockchain game to date, and the first of its kind to feature what game theorists call incomplete information." When a new player first arrives in Dark Forest, most of the universe-including potentially hostile opponents-is hidden. The hidden areas become visible only if the player explores them. Every time players move, they send a proof to the blockchain that the move is valid-without revealing their coordinates in the universe.

Since February 2020, more than 10,000 people have played. Some of them, like software developer Nalin Bhardwaj, have been inspired by the game's technical underpinnings to stay and work on the Dark Forest universe-and build new Dark Forest-inspired games. They see Dark Forest as the first step toward rich digital realities-some might call them metaverses-that are run by decentralized networks instead of company servers.

Dark Forest is not only the most complicated blockhain game, says Bhardwaj: I do not think there is an application on the blockchain that is more complex." By designing it to run on a blockchain, the game's creators also produced technical infrastructure that broadens the scope of how we might use blockchains to interact online, he argues.

To Bhardwaj and other true believers, Dark Forest is proof of several new concepts at once. First, it demonstrates how advanced cryptography can be used to add new features to online worlds. Developers and computer scientists inspired by Dark Forest are already exploring new games and applications that take advantage of zero-knowledge proofs.

Gubsheep and others have even launched an R&D organization, called 0xPARC (a reference to PARC, the storied R&D company that Xerox launched 40 years ago), to support this work. Bhardwaj recently did a stint as a 0xPARC intern.

The scope of 0xPARC is not limited to gaming. For example, one application the group is interested in is digital identification. Recall the passport example. Zero-knowledge proofs could make it possible to prove all kinds of things about yourself without revealing anything else. You could prove you were above a certain age without revealing your actual age, or that you have more than a certain amount of money in your bank account without revealing the actual amount. It could also be possible to use zero-knowledge cryptography to prove that you've run a machine-learning algorithm on a sensitive data set while keeping the data private, says Gubsheep.

A new vision for the metaverse?

Zero knowledge is also not the only focus at 0xPARC. The deepest thinkers about Dark Forest seem to agree that while its use of cryptography is genuinely innovative, an even more compelling proof of concept in the game is its autonomous" game world-an online environment that no one controls, and which cannot be taken down.

So far, Dark Forest has existed in temporary instances, called rounds, that last between one and two weeks. But since it exists entirely in blockchain smart contracts-computer programs that the blockchain stores and executes-a Dark Forest world could be deployed in such a way that no one would have the capability to stop it, says computer scientist and 0xPARC cofounder Justin Glibert. You could think of it like a Minecraft server but it can't be taken down," he says.

Once a smart contract is deployed, it's a bit like a robot that lives in digital space-one that can run forever. Unless the creator installs a mechanism that can be triggered to kill the program, it will keep running as long as the network exists. In this case, Glibert argues, the virtual world would be more like a digital planet" than a game.

What happens on a digital planet? Whatever the world's rules-its digital physics"-allow, he says. Dark Forest players have used its digital physics to build in-game marketplaces, tools that automate game functions, and even bots that can play the game themselves. It's also free for anyone to copy, modify, and build on.

Glibert's team at 0xPARC is focused on creating systems that make it easier not only for game developers to create autonomous worlds but also for the inhabitants of those worlds to interact and create.

Gubsheep says this is the natural development of the internet. The digital world is becoming the host of more and more of our most meaningful interactions," he says. But he wagers that people will be less likely to accept a version of the metaverse" that is governed by a company or any other centralized entity.

What they will want instead is a credibly neutral substrate for people to express themselves in relatively unconstrained ways and to self-organize and self-govern," he argues. That's a much more powerful vision of the metaverse to me, and one that I hope 0xPARC's experiments can contribute to."