Starcraft AI blog

Steamhammer is doing relatively poorly. The new version 1.4 is at about the same level as the tournament version 1.4a3, maybe a little worse. (It’s hard to tell, because the opponents have improved.) It is at the low end of my expectations. A slow start was only natural, since it had to learn for itself about many opponents that it previously was hand-configured to defeat, but it seems to be genuinely not improved. In reality, it is stronger in many ways, but it also has a few new weaknesses. The new weaknesses are from the opponent model’s mistakes and limitations.

The next opponent model feature, I’ve decided, should be fine-tuning the choice of openings against each opponent according to results. The opening recognition will provide instant counters when it successfully recognizes the opponent’s opening, and fine-tuning will sharpen the selection over time. Details still to be decided, though. After enough games to accumulate data, that should solve Steamhammer’s newly-added weaknesses.

More opponent model features will follow, as mentioned at the end of the original post on the opponent model’s workings and the post on a tree of openings.

Today’s overlong game against PurpleSwarm shows bugs on both sides. Steamhammer correctly predicted PurpleSwarm’s opening and played 5 pool, which put Steamhammer ahead and should have won. Instead of keeping the pressure on, Steamhammer droned up, went to 3 bases, and started to switch into mutalisks—it does that occasionally, it’s a choice. PurpleSwarm took advantage of the delay and recovered, overrunning Steamhammer’s bases with zerglings. Just after its natural fell, Steamhammer made an extractor there, which seemed wasteful but turned out to be key. Then, just before its main fell, Steamhammer hatched its first and only 2 mutalisks. There was not much play left for Steamhammer.

PurpleSwarm destroyed everything it found, but never found the extractor that was barely out of sight. Zerglings roamed the map checking bases, but didn’t look everywhere. PurpleSwarm also never mounted a defense against the 2 mutalisks. That makes 2 basic errors by PurpleSwarm. Steamhammer’s mutalisks slowly wore down drones and buildings, like water dripping on stone (watch the whole game if you have geological patience). The mutalisks sometimes went idle, which should never happen for more than 8 frames. And the mutalisks did not search for other bases, but only destroyed those already seen. That’s 2 bugs for Steamhammer. Steamhammer’s bugs proved less severe: Steamhammer won on points when the game timed out, since its mutalisks destroyed so much stuff over the long long endgame.

Steamhammer’s bugs appear to be in the tactical goal selection. These are features which usually work but failed this game (and I have seen other failures too). The code does not look that complicated, but I have fixed bugs in it before. I guess it is trickier than it appears. I did make one change to exploration: Air squads are now allowed to explore places which are not reachable by ground. That would not have helped this game, but it could help against an opponent whose last base is an island base, or which is hiding floating buildings in an inaccessible spot.