How did a hacker steal over $600 million from a crypto gaming blockchain?

Axie Infinity developer Sky Mavis announced Tuesday a massive breach of its Ronin cryptocurrency sidechain. An attacker used "hacked private keys" to break through Ronin's validator network, Sky Mavis says, transferring 173,600 ethereum (worth approximately $594 million at current rates) and $25.5 million in USDC stablecoin as part of one of the largest breaches in the history of cryptocurrency.

To understand the nature of that breach, let us take you on a crash course in the short history of Axie Infinity and the complex web of crypto standards and technologies that helped allow the exploit to happen.

So you can, like, make money by playing a game?

Axie Infinity has been cited as one of the early success stories in so-called blockchain gaming. Such games use decentralized protocols to track ownership of certain in-game items and generally let players have some control over the resale of those items.