Gamma Energy visits the Aperture Science East facility, built after GLaDOS gained sentience. The goal was to create a facility where GLaDOS' research could be examined and tested without harm to employees or other people who actually... mattered, without her knowledge. Pick up a prototype Portal Device and try not to die.
Really solid for the most part. The puzzles are fairly easy but still a lot of fun to play. It kind of loses it towards the end where you are going through the maintenance areas of the lab, it's kind of confusing and hard to figure out what to do.