Benn and I are huge sports fans, and this story got us thinking about why these collectibles mean so much to people. Simply put, sports provide moments that bring us joy, and trading cards immortalize those moments (or the players responsible for them). While the story told by a given card varies from collector to collector, its fundamental value remains the same: the ability to own a scarce representation of a memory we hold dear.

Benn and I are also long-standing crypto believers, so ownership and scarcity are two concepts we talk a lot about. We started imagining what a blockchain-based sports trading card game would look like, both agreeing that such a product would only be valuable if it had interesting new properties that were uniquely enabled by the blockchain. There are inherent UX tradeoffs when building on top of a decentralized ledger, and tacking on “blockchain for the sake of blockchain” ends up hurting your users without giving them anything exciting in return, which really sucks. If your project could exist using a traditional (centralized) database, you should just use that!

After some brainstorming, we came up with four properties of digital sports cards that could be uniquely unlocked by decentralization, and we’ve made these our guiding principles throughout the development of CryptoStrikers. We list them below, and explain how each has informed our final product.

1 - True Digital Ownership

It is clear that between what a man calls me and what he simply calls mine the line is difficult to draw — William James

Our possessions are an extension of us. However, this gets messy in a world where the things we own increasingly live online, hosted on servers we don’t control. What happens when your online photo storage service shuts down, or when your blogging platform decides to delete 10 years worth of your posts?

My card collection on display

Our Solution: Each of our unique cards takes the form of an ERC-721 token on the Ethereum blockchain, rather than a database entry on a centralized server. This means that as long as you control a card in your digital wallet, nobody can take it away from you, no matter what happens to CryptoStrikers. Proudly showcase your collection on your profile page, because those cards are irrevocably yours.

2 - Provable Scarcity

In the words of Nick Tomaino, “humans have a fundamental desire to own things that are scarce that other people want”. However, sports card rarity is typically tricky to prove in both the physical world (how many cards is Panini actually printing?) and on existing centralized digital platforms (when Topps BUNT says a card is 1 of 100, are they being truthful?).

Provably rare card tiers

Our Solution: Because the CryptoStrikers data lives on the blockchain, it is public by default, so anybody can verify the circulating supply of a given card. We also hard-code issuance limits into our smart contract, which ensures that we cannot inflate the supply of cards at a later date. Down the road, this enables us to do cool things like issuing a special card that is limited to fans who were at a given sporting event (example: after LeBron has a historic night), providing for an exclusive souvenir.

Soccer is a global sport, so it makes sense that a soccer trading card game should be able to leverage a global community, one where anybody can participate and where scarce digital assets move freely and securely across borders. While the current iteration of the Internet enabled the seamless transmission of information, we hope that blockchains enable the seamless transmission of value. Currently, sports cards both physical and digital are mainly transacted on eBay, where fakes abound and you need a bank account to participate. We can do better.

Lowballing Benn during testing by offering my duplicate Marcelo for his #1 of 8000 Salah

Our Solution: We took a page out of 0x’s book and built a trading feature that allows users to swap cards directly between their digital wallets, with no middleman and no possibility of receiving a fake card in return. Users create a cryptographically signed trade off-chain, and then share the trade to social media (Reddit/Discord/Twitter) or directly with their friends. A trade partner then takes that signature to our smart contract for on-chain settlement, and the cards are automatically swapped between the two users’ wallets. We hope this trading mechanism helps us build a new kind of trading card community, one uniquely enabled by this truly global liquidity pool.

4 - Extensibility/Interoperability

With physical trading cards, you can place them in albums, and… not much else. With current digital sports cards platforms, your cards are siloed to a specific company’s servers, so you can only use them in ways that company sees fit.

Our Solution: We’re standing on the shoulders of giants here, but the work the CryptoKitties team has done with the ERC-721 specification has paved the way for an entire generation of rare digital assets all built 1) on a public ledger and 2) using the same open standards. This means that anybody can see which CryptoStrikers cards you own and incorporate that ownership data into their own game — all without our permission! Benn and I are sports industry veterans (I was an early engineer at DRAFT, Benn most recently ran Business Development at Sportradar US), and although we didn’t have time to build out a CryptoStrikers fantasy game for the World Cup, we would love to see our users build unique games and applications on top of the cards they own. In the meantime, we’ve played with this concept of interoperability between digital assets by building a smart contract that allows users to redeem a spare CryptoKitty for a free pack of cards 😉