Deep Blue (a chess bot) in 1997. IBM’s chess supercomputer did not use techniques that would be considered true AI by the standards in 2020. Essentially it relied on “brute force” methods of calculating every possible option at high speed, rather than analyzing gameplay and learning about the game. However, it was important from a publicity point of view – drawing attention to the fact that computers were evolving very quickly and becoming increasingly competent at activities at which humans previously reigned unchallenged. (Deep Blue vs Kasparov: How a computer beat best chess player in the world - BBC News)

AlphaGo (a Go bot) in 2016. Gameplay has long been a chosen method for demonstrating the abilities of thinking machines, and the trend continued to make headlines in 2016 when AlphaGo, created by Deep Mind (now a Google subsidiary) defeated world Go champion Lee Sedol over five matches. Although Go moves can be described mathematically, the sheer number of the variations of the game that can be played – there are over 100,000 possible opening moves in Go, compared to 400 in Chess – makes the brute force approach impractical. AlphaGo used neural networks to study the game and learn as it played. (AlphaGo - The Movie | Full award-winning documentary)

Libratus (a poker bot) in 2017. Libratus is an artificial intelligence computer program designed to play poker, specifically heads up no-limit Texas hold 'em, and it is the result of continuous advancements thanks to several challenges on simplified versions of the poker game starting from 2005. Libratus was pitted in a tournament against four top-class human poker players for 20 days, 10 hours per day. It won about 1.8 million USD. Libratus exploits no-regret learning algorithms. (How AI beat the best poker players in the world | Engadget R+D)

AlphaStar (a StarCraft II bot) in 2019. AlphaStar is an artificial intelligence built by Google’s DeepMind that achieved a grandmaster rating in the StarCraft II video game after it was unleashed on the game’s European servers, placing within the top 0.15% of the region's 90,000 players. Unlike chess, StarCraft II has hundreds of 'pieces' that move simultaneously in real time, not in an orderly, turn-based fashion. Whereas a chess piece has a limited number of legal moves, AlphaStar has 10^26 actions to choose from at any moment. And StarCraft II, unlike chess, is a game of imperfect information where players often cannot see what their opponent is doing. This makes it unpredictable. (AlphaStar: The inside story)