Starcraft AI blog

Wuli’s zealot rush beats Steamhammer about 4 games out of 5. UAlbertaBot’s usually wins too. Carsten Nielsen’s wins fairly often, and Lukas Moravec sometimes plays a winning zealot rush. Steamhammer’s weakness is not the initial defense, which holds the zealots for quite a long time. It’s similar to games versus McRave; the weakness is in the transition to lair tech. Steamhammer ends up without enough drones.

Someday the strategy boss will be smart enough to understand the situation and make a safe transition. It will be easier if I improve Steamhammer’s defensive skills, which are simpleminded. But those things take time. In the short run, it’s easier to come up with an opening that beats zealot rushes. Then all Steamhammer needs is to know when to play that opening.

Bots should benefit hugely from opponent modeling, because other bots mostly play in stereotyped ways. Wuli and Carsten Nielsen never deviate from their rush builds. But Lukas Moravec, among others, plays more than 1 build. So to counter zealot rushes, a bot also wants plan recognition. If the scout sees 2 or more gates and a lack of other stuff (no gas, forge, or expansion), then the bot had better stay safe against a hard rush. If it sees a forge and cannons, it had better emphasize drones and hatcheries instead. Opponent modeling and plan recognition can be combined: Here are the plans the enemy has been seen to follow (described in some abstract way, such as the timings at which units appear). Based on scouting information, this past enemy behavior is the closest match, so let’s counter it. Since bots are predictable, simple opponent modeling is likely to give big leverage.

More about opponent modeling: If you know the opponent’s range of openings, then you can figure out how best to open yourself—what to do until you get scouting information and can adapt. Lukas Moravec never tries a fast rush, so you don’t need to stay safe against rushes. If the opponent never plays proxies (like most), then you don’t have to scout for proxies. If the opponent plays a mix of fast and slow openings, then you can try to estimate the best counter-mix with game theory. There are a ton of ways to gain advantage by knowing the opponent’s habits.