Portal 2 is a sequel to Portal, a bestselling 2007 video game. It is set in an apocalyptic future earth, where the protagonist is trapped in a science testing facility. This protagonist is a previous aperture science test subject, who eventually defeated an evil AI named GLaDOS, but was dragged back into the facility and put into suspension for around 50,000 years. Then Portal 2 takes place. Portal 2 contains a singleplayer story mode, as well as a cooperative testing initiative. I also has a test chamber building editor. It is a really fun game, Themed around the Aperture Science Handheld Portal Device, or portal gun, which creates intra-dimensional gates from one position to the other. Here are some pictures: https://en.wikipedia.org/wiki/Portal_2