Conversion Gel

A yet unnamed, third gel added to the Propulsive and Repulsion Gels is slated to be featured in Portal 2.

The third gel, if this link list of leaked achievements is to be believed is called "Conversion Gel", nothing at all is known about what this gel does.

Overview
The nature of this third gel is unknown so far, although it may involve walking on walls and ceilings, as Portal 2 reuses the paint featured in Tag: The Power of Paint.

Behind the scenes
Out of the three gels featured in Tag, only the blue one, allowing the player to walk on walls and ceilings, has not been converted for Portal 2. When asked during GamesCom '10 about the possible inclusion of a third gel and its nature being that of Tag's blue gel, Erik Wolpaw only answered that there would indeed be a third gel, but did not expand on its nature.

List of appearances

 * Portal 2