Last week, Reed Wilen, an elite gamer using the handle”Chicago” in Rocket League, a popular car soccer game, encountered a strange and disturbing new opponent. The player seemed like a novice at first, moving his rocket-propelled vehicle in a hesitant and clumsy manner. Then they caught and balanced the ball perfectly on the hood of their car, and dribbled it towards the goal at high speed with superhuman skill.
Not only was the other driver clearly a bot, he was ridiculously good. “It’s very confusing to play against,” says Wilen. “His perfect dribble would destroy almost any player.”
Wilen is one of the elite Rocket League players who have recently encountered the bot in competitive play. It’s not good enough to beat everyone just yet, but it can play at a high level, allowing less skilled players to work their way up to a higher ranking.
Rocket League is frantic and extremely tricky to play. Each player controls a car capable of impossible acrobatics in an arena where gravity and physics are apparently ridiculously set. The goal is to use your vehicle to maneuver a giant ball past your opponent and into their goal, a task that requires a lot of skill and patience. Sometimes two players work together as a team, making huge leaps, parrying desperately and accidentally colliding as they try to anticipate and counter their opponents’ own antics.
Top Rocket League players will often launch their cars through the air to move the ball to the goal, but Wilen says the bot he encountered appears to be specially trained to carry the ball across the ground. “The bot doesn’t really spin around a lot and it doesn’t jump in the air,” he says, apparently because it’s not programmed to do that or taught how to do it. “Instead, he waits for the ball to come down, then catches it on top of the car and executes a perfect dribble to the opponent’s net,” says Wilen.
The bot that Wilen and others have come across is called Nexto. It was given the ability to dribble and score using an artificial intelligence approach known as Reinforcement Learning. Starcraft. The technique has also been applied to more practical areas in recent years, including chip design and data center cooling. Reinforcement learning involves creating a program that can perform and improve a task at a basic level by responding to feedback as it practices.
The company behind it Rocket League, Psyonix, part of Epic Games, allows players to deploy bots to practice against. In 2020, it released an Application Programming Interface (API) to help developers build bots more easily. Last April, a group of Rocket League enthusiasts with coding skills announced RLGym, an open source library for building reinforcement learning bots Rocket League. Later in the year, the group released several open source AI bots, including a particularly skilled dribbler named Nexto.
