Machine learning software from OpenAI has beaten one of the world’s best players at the video game Dota 2. Elon Musk, who co-founded OpenAI, says that it is the "first ever … defeat [of the] world's best players in competitive e-sports." The Verge reports that Danylo Ishutin, the human player who got beaten, found the AI "a little like [a] human, but a little like something else" to play against.

OpenAI’s software mastered the game, which requires players to defend a base from their opponents, by playing a copy of itself. “We didn’t hard-code in any strategy, we didn’t have it learn from human experts, just from the very beginning, it just keeps playing against a copy of itself,” explains OpenAI researcher Jakub Pachocki in a video. “It starts from complete randomness and then it makes very small improvements, and eventually it’s just pro level.”

It’s an impressive feat, not least because Dota 2 requires making decisions based on imperfect information, unlike games such as Go or chess. But it’s not all good news. Some players have reported that they beat the algorithm after studying its play, and at any rate the AI can only play one-on-one, which is far simpler than regular five-on-five battles that require extensive collaboration. According to TechCrunch, OpenAI says that the five-player game is on its list of problems to crack.