Starcraft AI blog

Looking closely at the newly implemented queen play, I noticed a bug that caused delays in action. The queen would spot a good target and prepare to launch its parasite... then lose track of what it was doing and execute a move instead, find the good target again, etc. I fixed it to keep proper track of its intentions, and suddenly the queen’s actions were prompt to the point of being overeager: It would move into range and cast its parasite, then before the parasite landed, parasite the same target again! I had to fix that too; it was not enough to stick to targets which are not already parasited. Then I realized... oh... this must also be the long sought Third Defiler Bug. Queens and defilers have their own code, but they work about the same way.

Last fall I added defiler support. In the winter I fixed two serious bugs (see the zerg section) in defiler control. And I suspected that there was a third one, because defilers still reacted sluggishly. This is the third bug—I finally found it.

When the queen fix is properly generalized for defilers, I expect that defilers will start getting stuff done. As ground units they will still meander into traffic jams and struggle to coordinate with their food to consume, and dark swarm (which is extremely hard to use well) will still be restricted to narrow circumstances. Even so, I expect defilers to be much more active, more nearly what they should be.

So, as usual, the next release should have more improvements than planned.

Parasite works moderately well. On average the queen does not really pay for itself, but it’s a small expense (no research and the queen’s nest is there anyway), and I expect it will pay off in a few games. If the queen is lost, the strategy boss waits 3 game minutes before ordering up a new one, so even if the queen gets irradiated instantly it won’t be a big drain on resources. And every once in a while it can infest a command center.