Starcraft AI blog

I don’t want to write up any games that might be from the SSCAIT elimination phase, since it wouldn’t be polite to scoop the official announcement. But there are some good ones. In particular, CherryPi is starting to show its full opponent modeling skills, which are more sophisticated than we could see in the round robin phase with only 2 games against each opponent.

So here is a close game from the round robin, Steamhammer versus LetaBot by Martin Rooijackers. Steamhammer randomly chose a 1-hatchery lurker rush, a risky opening which often beats LetaBot quickly. This time, Steamhammer got distracted chasing the scouting SCV and put on no pressure with its early zerglings, allowing LetaBot to bunker safely at the front of its natural instead of in its main. Often LetaBot overreacts to the threat of the early zerglings, which is actually slight, and leaves itself weak to the lurkers. Here it defended nicely.

Well, not quite nicely. A bunch of marines stood in front of the defenses and were slaughtered by lurkers outside detection range of the turret. But Steamhammer is no smarter. As soon as the way to the bunkers was clear, zerg became overaggressive with the lurkers and lost them quickly. One lurker stayed outside bunker range and drained terran minerals into repair for a while, but as soon as marine range research finished in the academy, it died too. Steamhammer had rushed to lurkers with a weak economy (see the worker counts in the picture), so after an even-ish combat outcome, terran was ahead.

Followup lurkers behaved the same, killing infantry that placed itself needlessly in danger, then placing themselves needlessly in danger and dying. LetaBot expanded much later than it should have, letting zerg catch up in economy. But Steamhammer had been frittering its army away while LetaBot continued to build up despite losses, so terran was still ahead.

Finally the terran push came. The 4 sunkens and small zerg force can only delay the inevitable; the natural will definitely be lost. Zerg has 4 bases and an adequate economy, so it can attack the terran ball from all sides, but chances to save the game seen small.

The rear-placed sunkens were highly effective, because LetaBot assaulted them without regard to losses. Marines funneled between the buildings, suffering both sunken hits and splash damage from tank fire. Scattered zerglings ran in from every direction, but SCVs kept the tanks repaired. Steamhammer kept sending more drones to mine the natural gas, while LetaBot had expanded and added to its SCV count, so zerg was falling behind in economy again.

A small number of terran reinforcements were intercepted by zerglings taking a strange path across the map. The terran attack started to become disorganized, with some units running into the zerg main before the natural was reduced. In the picture, the spread-out tanks are under attack from both ends, and in the minimap is an engagement between zerglings and reinforcing marines, preventing the marines from joining up promptly.

The zerg army remained tiny, but it was LetaBot’s turn to rush in pell-mell without organizing its forces. Without marines supporting the tanks, and with adrenal gland research finished to increase the zergling attack rate, the small number of zerglings finished them off easily.

With the slow-to-replace tank mass destroyed, Steamhammer had enough forces to stop any followup attacks. The turnabout was sudden. Zerglings broke into the terran natural while the double bunkers were unoccupied, and simultaneously 1 lurker and a handful of zerglings erased the terran third. There was a little more drama with a last-ditch battlecruiser as Steamhammer was slow to deliver the finishing blow, but in the end an unnecessarily massive zerg force battered down the undefended terran buildings.

It was another narrow comeback. Those make fun games.

Next: Analysis of solid versus daring bots.