Valve publicly announced the development of Portal 2 as a sequel to the highly successful game Portal.
Portal 2 was released globally for Microsoft Windows, Mac OS X, PlayStation 3, and Xbox 360.
The official soundtrack for Portal 2, featuring music and songs from the game, was released.
Valve added Steam Workshop support to Portal 2 allowing players to create and share custom levels and content.
Aperture Science is established and begins its research into advanced science and portal technology.
The massive facility designed for testing and scientific experimentation is constructed.
Artificial Intelligence GLaDOS is activated to oversee and control the testing facility.
GLaDOS kills most of the staff and takes over the facility, halting human operations.
Chell awakens in the Aperture Science Enrichment Center and begins navigating the testing chambers under GLaDOS's observation.
Chell meets Wheatley, a defected personality core who assists her in evading GLaDOS.
Chell and Wheatley manage to remove GLaDOS by transferring her consciousness into a potato battery and fight against her control.
Wheatley assumes control but quickly becomes antagonistic due to his incompetence and corruption by power.
Chell confronts and defeats Wheatley, restoring control to GLaDOS, who surprisingly spares her life.
After the ordeal, GLaDOS allows Chell to leave the Aperture Science facility, ending the testing sessions.
