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.
So I finally got somewhere with Chamber 25 Advanced. The level design is complete, and the first playtest with my brother was a success. It took him over one hour to complete the level the first time. The gold time looks like it'll be around 20 minutes, and although it will require a few advanced techniques, (Most notably the Simple Peek-a-Portal and Crouch Jump) certain frustrating fling maneuvers have been pleasantly omitted.