Starcraft AI blog

In TvZ, sometimes terran stops marine production and goes with factory units (maybe with starport units), whether early in the game to play a straight mech strategy or later to switch to it. Usually terran lifts the barracks to get it or them out of the way. If you see a lifted barracks, that’s a clue to the enemy strategy. Seeing vultures or goliaths appear may be your first clue, but unavailable barracks say that marine production is stopped (or at least slowed), so it’s a stronger clue. It rules out marine-tank unit mixes.

I think human players can usually read the clue correctly, when they need to. Bot opponents go marine-tank often, so it may be a useful clue for bots. But it seems a little tricky to read with assurance. You can’t just say, “overlord spotted a lifted barracks, cancel lurkers,” you need to look at more context. Maybe terran is only rearranging their base, or moving the barracks to a blocking position for the sim city. (Though if it’s in a blocking position, you may see whether it is making units.) Even a floating barracks far from the terran base may be intended to land as a proxy, maybe making a couple firebats to toast some drones.

Maybe bots should take a graded approach. Early in the game, terran should have only 1 or 2 barracks. Seeing a barracks in the air is a big deal, and the longer it floats or otherwise produces nothing, the more sure you can be that infantry is deemphasized. Later in the game you should have a rough idea how many barracks terran may have tucked out of sight, or at least how many barracks the terran’s bases can support. The more flying barracks you see, the more confidence you should have that fresh marines will be few.

At least that’s what I would start with if I were coding it by hand. My plan is to draw inferences like that largely by machine learning.