Starcraft AI blog

I was testing a macro build on the map Baekmagoji, a 2 player map where macro builds are fitting because each main base has 2 geysers and 18 mineral patches—double the usual. (I routinely test on all kinds of maps.) Early in the game, Steamhammer suddenly panicked and canceled a hatchery to get its spawning pool immediately. What was going on?

The bug, or I should say bugs, turned out to be this: Because the enemy main was so rich in resources, Steamhammer decided “well, it’s a bit far away, but still it’s the best choice for my natural base.” When the scout found enemy buildings (“hey, that’s in my natural”), Steamhammer concluded that it was getting proxied. Panic! That was easy to fix; the chosen natural is not allowed to be a starting base. But wait, why was the first expansion hatchery already started somewhere else, so that it could be canceled? Because the choice of the natural base and the actual first expansion taken are not quite coordinated correctly; in some cases they can be different for no good reason. Ack!

Baekmagoji is a difficult map for bots. Another issue is that some of the mineral patches in the main are not reachable until other patches are mined out. It’s a clever design, but Steamhammer doesn’t understand it and tries to assign drones to minerals that they can’t reach. Well, that’s not important to fix yet. I can’t think of another competitive map that would trigger this bug (though more than a few Blizzard maps do). Also notice the neutral sunken colonies spreading creep, and the blocking temples and blocking minerals. Lots of tricks lying in wait.