Portal is a critically acclaimed puzzle-platform video game developed by Valve Corporation. Players navigate through a series of test chambers using a unique device called the Aperture Science Handheld Portal Device, which creates linked portals on flat surfaces, allowing for creative problem-solving and exploration. Set in the mysterious Aperture Science facility, players take on the role of Chell, who must escape while being guided (and often misled) by the AI antagonist, GLaDOS. The game is known for its innovative gameplay mechanics, dark humor, and engaging narrative, making it a landmark title in the gaming industry.