Starcraft AI blog

Walls have a lot of uses in Starcraft. In defense, walls can keep units out of your base, narrow a choke so that it is easier to defend, or create a maze so that units have to take long paths. In offence, walls can trap enemy units to keep them out of the fight or protect your offensive placements. Liquipedia has pretty good articles on walls (see the links at the bottom of the Liquipedia article)—they have almost enough information to design wall-building code.

Here’s how LetaBot walls on Ride of Valkyries. This wall blocks zealots, but the probe can pass between the barracks and the depot. LetaBot can lift or land the barracks to open or close the wall whenever it wants (though in practice it only lifts the barracks once).

Here is a standard protoss wall on Fighting Spirit, from a game between ever)P(Say and linearity. The zealot and probe are stopping up small gaps in the wall so that zerglings cannot get through; if zerglings did get past, they would run by the cannon and into the main. A potential disadvantage of the wall is that zerg can try to bust with hydralisks, killing the wall from outside cannon range before protoss gets storm, which would harm the zerg economy but force protoss to make many cannons.

Another common protoss wall is the pylon wall to hold off vulture harassment, or sometimes to block dragoons or lurkers. Zealots, hydralisks and zerglings can pass through. This one is placed at the outside ramp of a side expansion on Fighting Spirit to stop vultures. Partial pylon walls outside the natural to narrow the choke are standard versus terran. In some locations, pylon walls between a nexus and a cliff partially protect the mineral line against vulture harassment.

Here is a zerg wall. Zealots or dark templar have to circle around the wall to reach the sunken, funneled through a narrow pass. Zerg has different wall designs, often using a hatchery plus an evo chamber or a hydralisk den. Protoss can try to bust with dragoons.

Next: LetaBot’s wall code.