Sticky Gel (Mechanic)

Sticky Gel, known in the community as "Adhesion Gel" is a cut gel that lets you stick to surfaces covered in it. Object coated in it would not slide on Propulsion Gel. The Gel Originated from Tag: The Power of Paint and was ported to Paint (Project) which then was merged with Portal 2 in late 2009, but was cut in early 2010 as it made playtesters and developers sick and disoriented and did not work well with the Portal Gun during gameplay.

Origin
Sticky Gel originates from Tag: The Power of Paint, where it was blue. It would let you walk on walls and show an arrow indicator in the HUD to show your current orientation.

Leftovers
Before DLC1, the stick gel type was unused but still in the game, although non-functionally. The code for it still remains in the DLL files, and Prototype made a mod that partially re-enables it. All particles are still present, alongside sounds.

Media
Developer Video showcasing Sticky (Adhesion) Gel.

Adhesion Gel Demonstration 1

Adhesion Gel Demonstration 2