Starcraft AI blog

Steamhammer still has occasional devastating bugs in its reactions. Steamhammer-Sungguk Cha is an example. Sungguk Cha is an opponent Steamhammer usually has little trouble against. In this game, zerg played a not-very-appropriate lurker rush and handily held the initial marines. The zerg economy was weak, but the tech was there to cope with the next phase of vultures and wraiths, and zerg was in position to fight on. Instead Steamhammer fell into a loop, spawning zergling-overlord-zergling-overlord etc. With massive oversupply of overlords, a broken unit mix, and money piling up with no second hatchery in sight, only terran was in the game.

There are actually 2 bugs. The main bug is that an emergency reaction (“Oh no I have no army hurry hurry spawn stuff”) didn’t recognize that it had already occurred and fired repeatedly, dumping the long sequence of zergling-overlord into the queue. There are checks to prevent that sort of thing, and I haven’t spotted the mistake yet. If I don’t find it soon I’ll let it go until after the AIIDE deadline, because there are more urgent fixes to make.

As often happens, the primary bug triggered a secondary bug—bugs tend to cause unusual conditions, and unusual conditions tend to bring out more bugs. After a few extra overlords, any further overlords should have been recognized as excess and dropped—the idea is to drop planned overlords that are no longer needed after the army is destroyed in battle. That bug I have fixed. The issue is that Steamhammer was still technically in its opening book, though it was nearly at the end of the opening line. The opening book sometimes deliberately makes extra overlords (to save up larvas and produce mutalisks or lurkers in number all at once), so the check was turned off in that case. It was easy enough to add back a check that is loose enough that it doesn’t break openings.

As Willy Wonka said, so much time and so little to do. That must be why I haven’t posted in a week.