This article was written by Andrew Wagner, the founder of www.blockchaingaming.com

Background

There is a lot of history behind XAYA. It began in 2011 with Namecoin, to which core XAYA team members were major contributors. Forked off of Bitcoin, it took the concept of embedding critical data of the blockchain—despised by Bitcoin purists who view non-financial transactions as spam—and made it standard practice. The data was associated with strings of alphanumeric text in order to register ownership of things like identities and web domain names.

Not satisfied with these limitations, Namecoin was forked once more in 2013 to create Huntercoin, a massive multiplayer online game. The text strings now represented player-controlled characters, and the associated data was now the player’s most recent move. Combine all the moves stored on the blockchain, and players could calculate each other’s positions on the map without the need for mods, admins or servers.

This decentralized autonomous design had fascinating consequences. To many players it felt more “alive,” almost like a real world. When you added the fact that players could win huntercoins—which have real-world value—the stakes became very high.

At one point, there were 35,000 characters fighting over thousands of dollars worth of HUC per day. One player (or group of players) known as the Dominator conquered the world of Huntercoin and monopolized the coin supply. The community was forced to band together and try to defeat him by the rules of the game; when they lost, they had to fork the blockchain to balance the gameplay.

The real problems, however, were more fundamental. The gameplay itself was simple and boring, and you couldn’t easily build new games on top of the Huntercoin protocol. Scalability issues also made it impossible to expand the Huntercoin world without bloating the blockchain.

The Basics

XAYA was conceived in 2016 to solve these problems. Originally called Chimaera—from which its cryptocurrency, CHI, gets its name—it later underwent rebranding. The main network launched in 2018, and token sales that year raised over $3.3 million USD worth of BTC and ETH.

Although the project is open source, the core team behind it is organized under a Malta-based company called Autonomous Worlds Ltd. Some of them are legendary on bitcointalk.org; Andrew Colosimo was a major Namecoin contributor and the founder of Huntercoin. Daniel Kraft, who’s helped develop many open sources cryptocurrencies, has a PhD in mathematics and published blockchain gaming research in two peer-reviewed journals (1, 2). Others are highly experienced in the video game industry.

Many blockchain gaming projects have industry leaders on board, however, and some have significantly more funding. It’s the technology that really sets XAYA apart. Drawing inspiration from both Namecoin and Huntercoin, their platform really has no rival in terms of the variety of things it can do.

XAYA is currently the only blockchain gaming platform to allow completely trustless online play. Like Huntercoin, it does this by placing the gamestate—every item, character and facet of the virtual world that can be interacted with—all on-chain, stored as a series of modifiers. Just as we embed arithmetic in Bitcoin transactions to alter the ledger of BTC balances, so do players embed decisions in XAYA transactions to make their moves, calculating each other’s positions.

XAYA takes things a step further than Huntercoin, however. In Huntercoin, the map parameters and character abilities are hard-coded into the base layer of the protocol. XAYA, on the other hand, is a blank slate, capable of storing any type of data for any type of game. The game developers design the logic they want, and the players choose which sets of rules to follow, i.e. which games to play.

To accomplish this, XAYA takes a step back from Huntercoin and reimplements the naming system from Namecoin. Similar to Colored Coins, names are registered with a small fee of 0.01 CHI, which cannot be used again for other things. Data continues to be associated with strings of text, but instead of playable characters, the text strings are now player accounts. The characters, items and other information constituting your game data are thus automatically associated to your account; this is registered to your address, such that only the person with the private key can control it.

It’s hard to talk about the possibilities of this without sounding fanciful. Some blockchain game platforms just decentralize the probabilities, a concept known as “provable fairness”; others only decentralize the items, known as “true ownership.” XAYA allows developers to decentralize the whole game entirely, such that they couldn’t turn it off even if they wanted to. Any game can be transformed into a decentralized MMO.

Why would game developers want this? Aside from providing a great experience to attract players, XAYA promises to save developers a lot of money. Like with most blockchain gaming platforms, cryptocurrency payments can undercut traditional payment processors, and the open source model doesn’t take a massive cut of game revenue (unlike Steam’s 30%). By obsoleting the central server, XAYA also removes the cost of building and maintaining online infrastructure. There’s also no chance of it being hacked.

XAYA also provides a unified marketplace of game assets; items can be trustlessly exchanged directly via the protocol using another Namecoin-derived ability. Called “atomic transactions,” they are basically a multisignature arrangement: one output sends the item to the buyer, another sends CHI to the seller, and both have to sign. Everybody gets what they wanted or nobody does, and players can even trade entire accounts this way.

Since gamestates are separated, however, with different developers storing data in different formats, additional functionality is required to interact between them. For example, you might want to trade an item in one game for an item in another. In this case, CHI is used as an intermediary, requiring two transactions in rapid succession: sell an item in game A for CHI, and use the CHI to buy an item in game B. This provides more utility to CHI tokens.

Scalability

Critics of fully-decentralized games commonly argue that games are too big to put on the blockchain. CryptoKitties’ accidental debilitation of Ethereum is well-documented, and Huntercoin clients—despite only processing a single, fairly-simple game—were a nightmare to sync.

One remedy for this is quick and easy: the XAYA blockchain is divided into different games. Players only need to compute the states of games they’re interested in, with their data files growing in size for each new game they play, and shrinking again when they quit (if necessary).

XAYA’s true innovation, however, is what they call “game channels.” These work in a manner similar to Bitcoin’s Lightning channels, except they’re not designed only for payments. Players in a match track moves on a private channel; when the match ends, the results are inserted into the main chain via a single multisignature transaction.

While XAYA’s main chain has an average block time of 30 seconds, the “block times” on the channels are variable. For turn-based games, transactions are issued as quickly as players can compute their decisions; for real-time, they are issued as fast as your hardware allows, much like your TV operates by displaying dozens of images per second. The most progress a player might lose is the tiny moments between frames.

There is an upper limit to the number of parties that can feasibly be in a game channel, however, and it’s nowhere near the population of mainstream MMO games. That’s where an idea called sharding comes into play. When applied to blockchains and other types of online databases, it refers to storing data in bits and pieces on different computers, instead of everybody having a full copy of the ledger.

Now for all you gamers out there: do you remember when you had to load new areas of a map as you traveled across them? That was necessary because your machine’s local memory couldn’t process the whole map at once, so instead it came in chunks from your hard drive and/or an online server. Sharding will look similar in blockchain games.

Most immediately, you only need to verify game interactions between adjacent or nearby players; the rest of the game world is only affected in the long term. Players in other parts of the map need not know your position or status, and this might in fact be preferable in order to facilitate a fog of war effect in games. Players therefore only open game channels with other characters in their proximity, and locally only process transactions relevant to themselves.

Even when the blockchain is private, cryptographic verification prevents malicious players from adding false information to gamestates represented there. Players are mathematically incapable of building a block which includes transactions—AKA moves—that are invalid. Valid moves that would favor the opponent (Alice turns off her shield spell before Bob’s fireball strikes, killing Alice) cannot be forged because the transactions for them require signatures.

If a malicious player refuses to move, or only provides invalid moves, the honest opponent publishes a “dispute transaction” containing his or her valid next decision. The game channel then closes, and the malicious player suffers penalties (match forfeiture, banishment). The only problem is how to keep track of gamestate changes since the opening of the channel; the initial transaction opening it specifies that conditions are returned to their initial state (minus forfeiture penalties). This could be paradoxical if they have affected their environment.

The Lightning Network solves this problem using “commitment transactions,” which are signed by both parties such that either can broadcast it at any time. The previous commitment transaction is invalidated in the process. Similarly, the latest XAYA transaction in a game channel contains the final gamestate or a list of all previous moves, so the blockchain knows everything that happened upon the channel closing.

We still need to timestamp dispute transactions, however, to prove it’s been too long since a dishonest opponent has moved. This requires placing their hash values on the blockchain, consuming valuable data space. XAYA remedies this problem with ephemeral timestamps: even dispute transactions do not need to be included in the blockchain in their entirety; instead, they use disappearing Merkle trees.

This is an idea pioneered by Factom which I have nerded out on in the past. The hash values of many transactions are combined together into a single hash value, which can thereafter be used to verify any of the transactions included. Since all of them must have been known to create the “root” or “top” hash, we can be sure (if a transaction is provided) that it was valid, and that it existed when the root hash was inserted in the blockchain.

Hash values themselves are relatively tiny, and inserting them into the blockchain only requires a single transaction. This is still worth processing to miners, but divided amongst all the gamers playing on XAYA, the cost is negligible to them. Players only have to worry about the fees for opening and closing channels.

Astute cryptographers might still worry about the consequences for the size of the XAYA blockchain. In order to verify one “leaf” of a Merkle tree, it’s necessary to possess the entire branch connecting it to the root. That means in order to verify a transaction effectively, we need the hash values of the rest of the data in the block that transaction was confirmed in. This is actually not too bad because of how blockchains are organized.

XAYA aims to improve the situation anyway, however. Since Merkle branches do not affect the gamestate, It’s not necessary to keep them if we’re sure no more disputes will occur. With that in mind, Merkle branches will gradually disappear from XAYA’s overarching tree, each one lasting only as long as needed. Hence the name “ephemeral” timestamps.

The DApps

No console is complete without the games, of course. XAYA already has a couple flagship decentralized applications in store, and even one or two in the way of third party support. You can also test it out with a simple battleship derivative called Xayaships, which demonstrates how easily board games can be replicated. Developers are encouraged to copy their open source code.

As a player of the original Huntercoin, I can confirm that the XAYA client is much more efficient by comparison. That’s partially due to the proliferation of solid-state drives, though, which have made Huntercoin faster, as well. There were also less installation steps for the players to figure out, however, and I breezed through my demonstration of Xayaships without requiring much help. Maybe I’ve gotten better, too.

Leading XAYA’s pack of video games is Taurion, the spiritual successor to Huntercoin. In this space MMO, players scramble to collect resources, build, and conquer each other on a far-away planet. What makes it unique in that genre is that it’s completely decentralized, promising to allow a truly decentralized and autonomous game economy. It could become what EVE Online—the gold standard of player-driven space MMOs—should have been, had it been created in a better time.

We are still far from that reality, however, and the predictable storyline (three rival spacefaring civilizations compete to explore the galaxy) isn’t the issue. EVE Online’s economy is centrally managed by a trained economist; changes to Taurion, on the other hand, are a significant event requiring the consensus of the players. In addition to technical innovation, economic foresight will be required, much more so than traditional game developers might face.

They’ve got the basics down. Setting up the Taurion game client was as uneventful as the wallet client; like with Xayaships, there was a somewhat lengthy “catching-up” process, which I assume was it downloading transaction data for the Taurion gamestate. Budding cryptographers may recognize that this data wasn’t necessary just to run the wallet client, thus limiting blockchain bloat. Everything went smoothly after it was done.

The game itself is still rather limited, though, which is understandable for a first release. There is a simple, relatively-passive combat system, but the gameplay mostly revolves around what’s called human mining. In Taurion, it’s called “prospecting,” a provably fair process which involves players looking for hidden treasures beneath the surface of the planet. Although the process is slow-paced right now, the rewards are great: the competition going on right now has almost $10,000 worth of cryptocurrency in prizes, plus several other giveaways. As more players become attracted to the game, its player-driven environment grows more complex.

Another game on the list is Soccer Manager Elite, unsurprising given the XAYA team’s European background. It’s very similar to other sports management games—you must pick the players who will perform the best—except it’s on the blockchain, and it has more economics baked in. Players can not only play as managers or agents, but also as shareholders in teams. Shareholders ultimately govern a team by choosing its manager, and reap cryptocurrency rewards if their team does well.

There’s also Treat Fighter, which is a bit more mysterious at this point. Their code is still closed source, and they chose to do a lot of it from scratch instead of utilizing code freely provided by the XAYA team. It seems clearly inspired by the success of Crypto Kitties and other true ownership-based games, in that you build, collect and battle with creatures, which in this case are made of candy. For some reason it gets me excited, though, maybe because I enjoyed Chibi Fighters. And no central server will be required.

Tying it all together is a decentralized application called Xaya ID, or “XID,” for short. This solves the identity problem on peer-to-peer networks, allowing players to use functional usernames (Such as Alice or Bob) without being impersonated in games. The blockchain tracks the owners of the names, who can sign a transaction at any time to prove they’re legit. Traditional game developers might want this to limit the personal data they’re required to store, shrinking the target on their backs for hackers.

The Verdict

In some ways, XAYA is a lot like Nintendo and the Wii. So far, it relies more on flagship titles than third parties for games; there are also parallels between Xayaships and Wii Sports, free games at launch designed to showcase tech possibilities. Neither were intended to match the speed and power of gaming platforms that rely on more traditional design methods.

No blockchain gaming platform can match XAYA in terms of innovation, however. None are really even trying to match it in terms of decentralization. It seems safe to say that competitors will learn their lesson—Sony and Microsoft did from the Wii—but CHI holders will have already made a lot of money, first, and many developers will have already committed to XAYA integration.

Their flagship games also look extremely promising. Much like Mario has done for Nintendo, the cultural legacy of Huntercoin is likely to attract loyal fans old and new. Taurion has faithfully followed in its footsteps, and the strong decentralist values of their close-knit community will probably inspire more characters to join their roster.

Overall, Autonomous Worlds Ltd. is clearly a leader at the forefront of the current generation of blockchain gaming platforms. They’ve held that title before with Huntercoin, so it’s conceivable they might hold it for a while longer.