Starcraft AI blog

Steamhammer got its first win against Krasi0 after many many tries. The map was Python, where starting positions are important, and the two bots got neighboring positions. Steamhammer went 9 pool speed, as it does 10% of the time versus terran, and Krasi0 was unlucky and scouted the wrong way around the map. Zerglings ran past the scouting SCV before it could reach the zerg base. The bunker in the terran natural was late and never finished (a bunker in the main could still have saved the game). Once zergling speed completed there was no hope for terran.

That apparently used up Steamhammer’s supply of luck, because it was immediately tied up in a string of losses. The loss against XIMP showed a bug I hadn’t seen, where Steamhammer repeatedly tried to take the third base that is a crucial part of its build order, but each time the drone lost interest and went home. Some weird macro bugs are lurking.

The most informative loss was another game against Krasi0, where Steamhammer first gained a winning advantage, then lined up its bugs and limitations in a row and held a parade. This time Steamhammer opened 12 hatch into 2 hatch muta. The bunker was again late, this time without excuse (is it a newly-introduced error?). The initial 6 zerglings got SCV kills that they did not fully deserve and, more importantly, slowed mining for a time as SCVs were pulled. With more smarts they could have stayed in the terran base and marauded for a time.

When the mutalisks came out, Steamhammer’s eyes lit up with crazed aggression. It flew over the bunker to kill every SCV that came near while ignoring the bunker itself and probably laughing maniacally. If it knew to fly to the mineral lines instead it could have won on the spot, but as it was the loss of workers set terran far back for the middle game. It was a decisive advantage and would have been a sure win with good followup.

Krasi0 countered the mutas with goliaths, which Steamhammer countered with hydralisks, which Krasi0 countered with tanks. That’s how you play the game. Steamhammer went up to 4 bases and brought out ultralisks while Krasi0 was still on 2 bases. Here you can see that Steamhammer has a larger army and more workers, and the production tab shows that zerg is outproducing terran even though minerals are accumulating. The terran 3rd command center is under construction in the lower left natural.

In the later game, Steamhammer, showing the other side of its mad streak, made 3 deadly mistakes and a bunch of smaller mistakes. Avoiding any of the 3 deadly mistakes might have been enough to win.

1. Steamhammer chose the unit mix hydra-ultra and became pinched for gas and unable to spend all its minerals. I overlooked a couple of important factors in the calculation. Hydra-ultra is useful in rare situations, and especially in situations nothing like this one. With zerglings instead, the zerg army would have been larger and deadlier and there was likely nothing Krasi0 could have done to hold it off.

2. Due to a bug, zerg was unable to take a 5th base. This bug I’ve seen before; it is not the same one as against XIMP. Getting the 5th gas would have made hydra-ultra more playable.

3. Zerg never scouted the terran 3rd base. It’s a limitation; I haven’t gotten around to middle game scouting yet though it’s a basic skill. See the expansion attempt, kick it down before it starts with a few units, starve out the terran. The hydra-ultra army should have been enough to keep the terran army bottled up if a few zerglings spotted expansion attempts.

Here’s another weakness: This is the 4th pair of scourge to chase this dropship, and the scourge is veering away for no reason. The 5th pair finally caught it. Suicide missions are hard to recruit for. Steamhammer showed hesitation with scourge and in shutting down vulture harass. In this picture, Krasi0 has turned it around and is winning by a mile.