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.
While some puzzles are interesting and make you think a bit, the fact that there's not much new here makes this mod not much fun to play. Most test chambers are too simple and require little thought. The story is nonexistent here. Basically, it's a watered-down version of Portal that is not worth playing, unless you are slightly stupid. Don't get me wrong, there are some genuinely fun puzzles, but the majority of them just aren't enjoyable.