Surfaces

Each level within the Portal series consists of surfaces. Typically, a portal can be shot on any light-colored flat surface, whereas an uneven or dark surface cannot be used in this way. These are used as the basic structure of any given puzzle.

Gels
As introduced in Portal 2, Gels can be applied on any surface to modify its attributes.


 * Repulsion Gel is a blue gel that bounces a player or object away from the surface.


 * Propulsion Gel is an orange gel that accelerates objects touching it, allowing players to run forward at high speeds.


 * Conversion Gel is a white gel that allows portals to be placed on surfaces that portals normally cannot be placed.