Starcraft AI blog

Steamhammer has superhuman macro, or at least, its macro skills are far beyond those of human players around its level. I think pro-level zergs can probably macro better than Steamhammer in many situations, because of superior planning. But Steamhammer is utterly superhuman in some aspects. For example, humans can’t do mining optimization after the early game. And the bot can set every drone to work on the first frame that the drone becomes commandable.

And yet, and yet! Steamhammer’s macro is far from optimal. It feels strange that it can be at the same time so good and still have so much room for improvement. It’s not something I need to work on soon, because it’s a relative strong point even compared to other zerg bots, but in the long run there are steps to take.

For one, Steamhammer does not do all the mining optimizations that it could. Some bots ranked above it have put considerably more effort in.

For another, there is a limitation in the production system that it can only produce one queue item per frame (except commands; it can execute commands in the same frame as another queue item). The limitation reduces bookkeeping and simplifies the code. Usually, it makes little difference. When Steamhammer saves larvas to produce its first 3 pairs of zerglings, it hardly matters that the second and third pairs start a fraction late. But in the late game, occasionally there is a sudden need to produce many zerglings at a time when all the needed larvas are available (because production has been limited by gas). The last zerglings in the queue may be started over a game second later than they could have been, and that could affect the fight. It’s hardly a critical weakness, though. I’ll rework production eventually, but it is low on my priority list.

The big macro weakness is that Steamhammer does not plan ahead. It makes hatcheries and overlords at times decided by heuristics. The heuristics are not bad, but for hatcheries in particular it often ends up with too few or too many—commonly, too few and then it overcorrects and gets too many. It’s possible to do much better by predicting the needs of future production and adding hatcheries just in time. It could be tricky, because future production depends on how the game will go, which depends on the opponent’s play. Even if you knew exactly what combat unit mix you want (which you can’t be sure of), there’s a risk that you might lose drones and need to replace them, and drones are larva-intensive because they are cheap. But still, it’s definitely possible to do much better than Steamhammer’s current play. That change is sort of in the middle of my priority list.

Even the greatest strengths are not so great. It’s a hard game.