Featuring complicated puzzles, a science fiction setting, and a passive-aggressive robot named GlaDOS, Portal is designed by Valve Entertainment. Players control Chell, who used an Aperture Handheld Portal Device to solve puzzles set forth by GlaDOS, who promised a non-existent cake when they are all completed. Portal spawned a highly anticipated sequel, as well as a fan base that created real world interpretations of many of the devices shown in the game.