Starcraft AI blog

Steamhammer versus BananaBrain on Moon Glaive was a fun back-and-forth game. Well, it was Randomhammer as zerg, that’s Steamhammer.

Steamhammer opened with a fast hatchery before pool, preparing zergling aggression. BananaBrain was also aggressive; it hid 2 gateways on the left of the map where they were unlikely to be scouted early. The gateways were more or less midway by ground between the 2 bases where zerg might be.

The zerglings outfought the zealots, then made a beeline for the protoss base, where they wrecked the economy. Protoss was left with 1 probe mining and 1 more in production.

But protoss had still been producing army during the attack, though the units were too far away to defend the main. It’s the drawback of a proxy opening: Close to the enemy means far from home. Steamhammer did not see the units and concluded that it was safe, so it started a third base (see 8 o’clock in the minimap), added a hydralisk den, and morphed a lair in its natural. A good human player would have predicted the protoss army size and been ready for it, but bots to date are weak at inference. Steamhammer could not save the lair in its natural and threw away units trying, then pulled together a defense in its main barely in time. BananaBrain ran by the sunkens to attack drones, one of its great skills, and it was zerg’s turn to fall behind in economy. Notice how much the protoss probe count has recovered. The zerg drone count fell to 5 shortly after the picture.

Three drones escaped the carnage and ran across the map to the hidden zerg third, which protoss did not yet know about (though a human player would have guessed its general location from the direction of arriving units). After a short distraction when a small zerg squad again attacked the protoss main, BananaBrain put heavy pressure on the defended zerg main. Both sides were racing to rebuild workers and trying to afford tech.

It was around here when BananaBrain repeatedly tried to expand, and Steamhammer’s patrolling Recon squad repeatedly denied it with only a few units. Protoss chose to keep attacking rather than defend an expansion. BananaBrain has added tech and sent out corsairs, and zerg protected its overlords with a spore colony in the main. Steamhammer’s mineral bank of 900 is a sign that it is short of hatcheries—it knows that, and wants to add hatcheries.

Needing more hatcheries, Steamhammer also tried to expand, in a rather strange pattern where the first hatchery at a new base was offset and the second one placed at the base location. The natural was denied, then a new base at 10 o’clock was about to be killed by zealots—when a scouting observer finally ran down the left of the map and discovered the hidden base, now bustling with drones. The protoss army suddenly had a more alluring target, and ran there to raze it.

But Steamhammer had mined its third base for most of the game, and BananaBrain had never been able to expand. The protoss main was dry, and the zerg 10 o’clock now had a half dozen drones at work, and it shows in the production tab. Steamhammer scourged the sky of corsairs, defeated the zealots with hydra-ling and a few mutalisks, and tore down the proxy gates before finally tackling the protoss main.

Whew, no big fights because of the damaged economies, but an exhausting struggle. Either side could have won easily at various points with smarter play at that moment.