Starcraft AI blog

Among SSCAIT tournament watchers, the talk of the moment is of Iron’s two surprise defeats against zergs Steamhammer by me and GarmBot by Aurelien Lermant. Iron got unlucky 2 games in a row.

In the Steamhammer game, Iron became overcautious against the few early zerglings, bunkered its ramp, and was late with its vulture attack. Provoking reactions like that is one of the reasons Steamhammer makes zerglings. When the mutalisks came out, they soon had enough numbers to safely break the bunker and then were free to ravage Iron’s base (they could have gone ravaging from the start, but they were obsessed with the bunker). Iron’s vultures moved in and quickly wiped out every drone, but the mutalisk swarm split up, some cleaning vultures and the rest cleaning the terran base. Steamhammer won with empty bases but unchallenged air supremacy. In my testing, Steamhammer has never won against Iron with this build order—Iron got unlucky, or perhaps a late change weakened its play in this situation.

In the GarmBot game, GarmBot randomly expanded to Iron’s natural and built a sunken that covered the ramp. Iron was again overcautious: It double bunkered its ramp and blocked with vultures and many SCVs, and sent no vultures past the sunken. It seemed in no hurry to get tanks and blow away the sunken. Mutalisks showed up and started picking at a supply depot; nothing stopped them. But the lethal blow did not come until lurkers arrived and burrowed in good position on the ramp. There was no detection. Lurkers defeated the blocking units and cleared the bunkers while mutalisks killed the engineering bay, and then there was no hope. Iron reacted poorly to GarmBot’s bizarre expansion and GarmBot followed up well.

It’s a hard game! Even a bot as well-rounded as Iron is not prepared for everything.