Starcraft AI blog

I got my SSCAIT wish and saw the first Steamhammer versus Killerbot and Steamhammer versus XIMP games today.

Steamhammer versus Killerbot by Marian Devecka: Would my counter-build work? In my tests Steamhammer wins with it about half the time. Killerbot went with its +1 speed lings and Steamhammer opened 11 pool and held with its own slow lings while teching to lair. Timing is critical—12 pool is too slow on some maps! In this game Steamhammer managed to sneak in a drone kill while Killerbot’s lings were busy chasing the scouting drone (UAlbertaBot doesn’t do that natively, I had to improve the decision making). Steamhammer added 2 sunkens for protection while getting mutalisks—it still had only 1 hatchery, while Killerbot was headed for 3 hatcheries, and it is impossible to hold without static defense. Steamhammer’s first 3 mutalisks hatched and headed for the enemy base, and as soon as the flyers were safely out of range to intervene, Killerbot’s zerglings attacked! Steamhammer pulled drones to defend and lost every single drone, but the sunkens held and the base was left barren but secure for the moment. The 3 mutalisks killed all of Killerbot’s drones in return and then tore down the enemy zerg base with excruciating slowness—Steamhammer won a close game. Steamhammer-Killerbot games often go down to the wire like this in my testing; I’ve seen one side or the other win with only 1 or 2 buildings left bleeding onto the map. But without the special-purpose counter-build, Steamhammer loses every game; Killerbot is far superior in tactics and robustness.

Steamhammer versus XIMP by Tomas Vajda: Steamhammer opened with 3 hatcheries before pool, the only bot I’ve seen play this logical response to forge-expand. (Though I saw auxanic open unsoundly with 5 hatcheries before pool!) XIMP cannoned up for carriers, as always. I hadn’t tested this matchup, so I wasn’t sure what would happen. Steamhammer went hydras with +1 attack, and soon had enough to tear down the cannon wall (slightly before +1 finished, annoyingly), wipe out XIMP’s natural, and start on the main. That’s what I intended, and I’m pleased it worked. XIMP seemed about to fall, but suddenly the first carriers started to make a difference—they finally had enough interceptors. The hydras did not have critical mass to fight carriers and were cleared from the main. At this point, Steamhammer had 6 bases though not enough drones to saturate them, and XIMP was mining minerals with 6 probes and gas with 3. Steamhammer was still winning by a mile.

Steamhammer then won when XIMP overstepped a time limit, taking too long on a frame. That was disappointing. :-( I’m not sure how the game would have turned out. Steamhammer was still ahead but was playing like an idiot, and XIMP did finally re-expand to its natural and may have been able to add carriers before Steamhammer could take the rest of the map and start to make progress.

After these two uncertain wins, Steamhammer played against protoss Ian Nicholas DaCosta, a weaker bot which it had beaten in their previous game. Steamhammer got unlucky with base positions and scouting, placed its 3rd hatchery directly on the path that zealots were taking toward its main, and lost. Luck runs both ways!