Portal is a puzzle-platform game developed and published by Valve Corporation. The game is set in the Aperture Science labs, a mysterious and seemingly abandoned research facility, and follows the story of a test subject named Chell who must use a portal gun to solve increasingly complex puzzles and escape the facility. Portal is known for its innovative gameplay, which allows players to create portals on certain surfaces and use them to traverse the environment, as well as its dark and humorous narrative and characters. The game was released in 2007 and was well-received by critics and players, who praised its unique gameplay, storytelling, and design. It has since been re-released on multiple platforms and has spawned numerous sequels and spin-offs.