Rexaura

Rexaura is a modification for Valve's Portal featuring a single-player campaign through an alternate world of Aperture Science. It contains 20 new chambers centered around high energy pellets. Players familiar with Portal and Portal 2 will once again be put to the test because Rexaura introduces a wide array of new testing elements that will force you to sharpen how you think with portals.
Rexaura is designed for those who have completed Portal. The puzzles are intended to be challenging to solve but easy to execute once you know the solution.