Starcraft AI blog

AIST S4 starts tomorrow. AIST is a different style of tournament from AIIDE, and I prepared differently for Steamhammer’s specific opponents. From the competitor’s point of view, AIST is a sequence of best-of-3 matches until you lose 2 matches—or win in the best-of-5 final. Steamhammer is unlikely to face the same opponent twice. With only a few games per opponent, Steamhammer’s deep library of builds is irrelevant.

I could have tuned the learning system to work well in short matches, as PurpleWave has done. Instead, I decided it was simpler to disable learning and use Steamhammer’s classic enemy-specific opening selection, which has gathered dust ever since learning was implemented in Steamhammer 1.4. Once I decided, I completed all the prep in a matter of hours. For each of the 5 opponents, I selected between 3 and 5 openings that were different and had high winning rates (except versus Stardust, which Steamhammer almost never defeats, where I picked what I hoped might have a chance). To choose, I looked at saved learning data for Steamhammer and Randomhammer zerg on BASIL, and for Steamhammer on SSCAIT, because each instance came up with different winners thanks to random sampling. Steamhammer will choose randomly from the openings for each opponent, according to probabilities I set, which sometimes vary depending on the map size.

For those who examine the tournament games, these lists may make the builds easier to interpret.

Stardust

• 9PoolHatchSpeedAllIn (Styx build)
• 10Hatch
• 3HatchLingExpo
• 3HatchHydra
• 2x10HatchAllIn

BananaBrain

• 2x10HatchSlow
• 10Hatch
• Over10HatchBust (zergling bust)
• 3HatchMutaPure
• OverhatchExpoLing

PurpleWave

• ZvZ_Overgas9Pool (one hatch muta)
• 11HatchTurtleHydra
• 9PoolHatchSpeedAllIn (Styx build)

Dragon

• AntiFact_2Hatch (2 hatch muta specialized to beat factory builds)
• AntiFactory2 (3 hatch hydra into muta)
• 2HatchLurker
• 3HatchLurker

WillyT

• 9PoolLurker
• OverpoolLurker
• 11Gas10PoolLurker
• 11HatchTurtleLurker
• ZvT_3HatchMutaExpo

Steamhammer has virtually no chance to beat Stardust. I’m guessing that Steamhammer has maybe a 20%-30% chance against PurpleWave or BananaBrain, and a better than even chance against each of the terrans. Notice the lurker builds, making use of Steamhammer’s stepped-up lurker skills.