Glacier Gorge is the fifth zone in the game, unlocking at 400 Starpower.
Units unlocked here
As a battleground
Glacier Gorge is a cramped battleground with many chokepoints: one going from each SENSO-Gate to the opponent's Extractors, and one in the middle. Creating the latter chokepoint is a line of gaps, and forming the middle checkpoint are a pair of mountains.
SENSO-Gate and Extractor locations
This map is divided into 4 quadrants with the chokepoints. The SENSO-Gates lie on the top-left and bottom-right quadrants. Both friendly Extractors lie on the bottom-left or top-right corners.