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.

GarmBot was reuploaded twice recently on SSCAIT. It looks as though it is under development again. Woohoo! Its description has added the message “Now with some lurkers. Big update coming to upgrade to BWAPI 4.1.2.” And I did see it build lurkers, which could spell trouble for some opponents (ones that GarmBot didn’t already overwhelm, I mean!).

GarmBot’s strategy is unsound, of course, but it’s also unique and delightful. It has a lot of room to improve without varying from its extreme macro, every-unit-for-itself game plan, so I’m interested to see how far Aurelien Lermant will go. Will some units get better micro or better decision-making? Will it make cleverer choices about which units to make where, such as not hatching drones to die instantly at a base that’s under attack? I would be interested to see whether it helps at all to build defensive units at a base that’s under light harassment and to waste as few resources as possible at a base that’s under massive attack—improvement or “so what?”

Not to put impossible expectations on anybody, but I can hope.

Update: The current GarmBot seems cleverer in some ways. For example, it is smarter with overlords. It’s also less aggressive about expanding and less successful overall. That’s OK—when adding ideas to a performance program it is normal to make the program worse at first, even when the ideas are good. The rest of the program may be optimized for the old behavior, and then you need a lot of updates.