Starcraft AI blog

Here are a couple of updates on top bots before I return to Overkill’s reinforcement learning.

Iron

For a while now, Iron has been playing a different strategy against protoss, going 2 barracks plus academy and attacking early with marines and medics rather than its traditional vultures. I’m a bit slow, but I finally realized why: It was having trouble against dragoons. Dragoons, adding observers in time to detect mines, are a strategically sound counter to Iron’s early vulture play, where tanks come late. Bereaver was handing Iron a string of losses with dragoon play. Time to switch it up!

Bereaver poked with 2 zealots but was unable to land a single hit against accurate micro.

Bereaver expanded early. I thought its force of 4 dragoons plus probes could have held off the marines, but it would have needed coordination and micro beyond the state of the art. Instead Bereaver lost its natural and was set back.

Iron tried to force the ramp while expanding, but didn’t have a big enough edge and was pushed back. Bereaver counterattacked and tried to get ahead with a double expansion, but tanks came out and Bereaver was never able to catch up. Bereaver strangely made a robo support bay early but did not build any reavers until much later, adding to its disadvantage—this game was played before the reupload below.

The dragoon opening is still sound against barracks play. Dragoons are versatile. But fighting the infantry calls for excellent micro with focus fire, and even Bereaver is lacking. Skynet is fairly skilled, but Iron’s new opening smashes it.

Bereaver

Bereaver was reuploaded yesterday. The new version’s first game was against Tyr by Simon Prins, and I immediately saw plays I hadn’t seen it make before. Bereaver went double robo.

Bereaver’s shuttle-reaver micro is not fluid like ZerGreenBot’s, but sharply goal-directed. Tyr vainly struggled to save itself, not realizing that it had to cover the reaver drop zones and come up with some kind of air defense. Every time Tyr unsieged, the reaver dropped, fired, was picked up instantly, the scarab skirted around the minerals—boom. By the time the second shuttle appeared with 1 zealot inside, it was already too late for terran.

The tanks at the top are approaching, too late to defend. As for reaver shots, sometimes they dud out. And sometimes they do this.

Reaver drop is crazy complicated. In time, I expect Bereaver to learn how to drop in the teeth of sieged tanks: Drop a zealot first. Tanks fire. Zealot says “ow!” Reaver drops and has time to fire before the tanks can reload. Terran defense has to be on the ball!