Nautilus, 2017: "Psychologists found that video games that allowed players to play out their “ideal selves” ... For the British artificial intelligence researcher and computer game designer Richard Bartle, the kaleidoscopic variety of human personality and interest is reflected in the video game arena. In his 1996 article “Hearts, Clubs, Diamonds, Spades: Players Who Suit MUDs,” he identified four primary types of video game player (the Killers, Achievers, Explorers, and Socializers)."

Nautilus, 2017: "Psychologists found that video games that allowed players to play out their “ideal selves” ... For the British artificial intelligence researcher and computer game designer Richard Bartle, the kaleidoscopic variety of human personality and interest is reflected in the video game arena. In his 1996 article “Hearts, Clubs, Diamonds, Spades: Players Who Suit MUDs,” he identified four primary types of video game player (the Killers, Achievers, Explorers, and Socializers)."