Hackers took roughly $620 million worth of cryptocurrency from a network that processed in-game transactions for Axie Infinity, one of the most popular NFT video games. It was revealed on Wednesday that an ongoing investigation suggests the attack was "socially engineered," rather than caused by a technical glitch. 

Axie Infinity and Ethereum blockchain are connected through the Ronin network, used for transactions and cryptocurrency transfers in and out of the game.

According to Ronin's blog post, the attackers made off with 173,600 ether and 25.5 million USDC. Axie Infinity's Twitter page also confirmed the attack. Ronin explained in its blog post that it is working with Chainalysis to track stolen funds.

Axie Infinity is a Pokemon-like video game played on a computer where players breed and battle digital monsters called "axies" that are linked to non-fungible tokens (NFTs). Players can earn cryptocurrency in the game, which can be traded on some cryptocurrency exchanges outside of the game. 

In 2021, the number of NFTs that passed through Axie Infinity was $3.5 billion, according to Business Insider India. There have been concerns raised about the stability of Axie Infinity, as a new player may be needed to support the game's economy. 

Aleksander Larsen, COO of Sky Mavis, told Bloomberg that the company will reimburse players whose funds were lost as a result of the hack. "We are fully committed to reimbursing our players as soon as possible," Larsen told Bloomberg. "We're still working on a solution, that is an ongoing discussion."