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After Go developers want to beat StarCraft 2 Players: The AI AlphaStar can compete in the real-time strategy game with the best 0.2 percent of the players – even without simplifications.

The Artificial Intelligence (AI) AlphaStar plays the computer game StarCraft 2 better than 99.8 percent of all human players. A team around Oriol Vinyals reported by the Google subsidiary DeepMind in the journal “Nature”. To train their AI, computer specialists use a combination of different machine learning techniques-reinforcement learning, multi-agent learning, and imitation learning. In doing so, they first introduced the basic features of the computer game to the neural network with anonymized game data of human players. Afterward, they repeatedly had several agents compete with each other, developing new strategies in a trial-and-error process to win as frequently as possible.

AlphaStar is not the first AI to master a game on the professional level. In the spring of 2016, AlphaGo, also developed by DeepMind, beat the world’s best Go player; In 2017, AlphaZero, a generalized version of the successor program AlphaGo Zero, defeated the world’s best chess computer.

StarCraft 2, which is one of the most complex and successful strategy games in the world, has been posing much more challenges than chess or Go for years, due to its gameplay mechanics. It does not run in a turn-based way, it works in real-time, and players never have the opportunity to see the entire playing field. The three playable Terrans, Zerg and Protoss races each have separate units that need to gather resources to build buildings and stronger units and defeat their opponents in combat. Depending on the faction different tactics lead to victory.

In early 2019, DeepMind introduced a variant of AlphaStar that could compete with two of the best StarCraft players in the world. However, the AI ​​played unfair: Unlike her opponents, she was able to survey all visible areas of the field at the same time and also act inhumanly fast. Besides, she could only play with a faction on a single card of the game.

Then DeepMind developed a new version of AlphaStar, which has to cope with similar limitations as human players: For example, she controls the camera itself and can not make more moves per minute than a human StarCraft player. As of July 2019, the AI ​​finally competed anonymously in ranked matches against real StarCraft players – reaching the top league in the league table with all three races, comprising only the top 200 players from each of the five server regions.

“The study on AlphaStar is methodically very well constructed and carried out,” says Kristian Kersting, head of the Machine Learning Department at the Technical University of Darmstadt. “It shows that hybrid AI systems – systems that combine various AI techniques such as symbolic search, reinforcing learning, and deep learning into a single system – can master complex real-time strategy games. Maybe not all, but at least StarCraft 2. “The computer scientist Marcus Liwicki from the Technical University Luleå in Sweden also finds the experiment interesting in principle. However, he doubts that the limits set by the DeepMind developers of their AI are really fair. »The click-through rate is around 270 clicks per minute. While this is a value that professional players can achieve, most of the clicks are empty clicks to stay active. It’s hard to imagine people performing at least four meaningful actions per second across the length of several games. “