Aperture Tag: The Paint Gun Testing Initiative is a community-made mod for Portal 2, inspired by TAG! The Power of Paint. The familiar Portal 2 gels are now contained within the Aperture Science Paint Gun Device and it's your job to test it out!

Featuring a new personality-core and an original story with 27 polished levels; the mod offers an exciting and fun experience in varied and interesting new locations throughout Aperture Science.

Introducing gels as the core gameplay mechanic completely changes the way you solve puzzles, explore, and survive all the challenges thrown at you!