SC2Mapster

Zergexpocity is a measure of how awesome the expansion options on a map are for Zerg.

In general, Zerg wants to expand away from opponents, either to the side or actually further than the Zerg's main.

Things you want UP
main to opponent main
nat to opponent main
third to opponent main

Things you want DOWN
main to nat to third

Actually, its more interesting than this, but the idea is to take all these measurements, where each base adds more weight than the last, and quantify whether the map in general appears to favor Zerg.