Portal: Revolution is a free to play mod for Portal 2. This fully featured original campaign plays before Portal 2 in the dead and decaying Enrichment Center.
Played for 30 minutes and got to the 6th chamber. It’s a lot of fun, but I’m not a huge fan of the Aperture Center voice. It just seems like it’s just phoned in compare to GlaDOS, Wheatley or Cave Johnson. The game itself is great with some new challenges!