Starcraft AI blog

In yesterday’s post, LetaBot commented “Pretty easy to hold as long as you pull back [hurt workers].... After all, you can outproduce the opponent.” Of course the details are more complicated than that; you have to get your workers to coordinate to some degree, at least pulling the right number to fight. But in substance, it’s true. The worker rush is not a sound strategy and can be defeated every time. Worker rush bots so far (Stone, then a LetaBot version, now PurpleTickles and Yuanheng Zhu) have found new wrinkles and scored wins against top veterans, but actively developed veterans quickly patch their defense skills and recover.

Even so, it can make sense to play a worker rush, as an option against some opponents. As PurpleWaveJadien also commented, in a round robin tournament “getting an additional win versus weaker opponents is as good as getting an additional win versus stronger opponents (and easier).” The worker rush makes sense because of the economics of bot development.

Think of it from the point of view of a new bot author. Your creation is freshly uploaded to SSCAIT and it doesn’t have many skills yet, but it does win sometimes. What should you work on next? It depends, but probably basic macro and micro skills will lift your elo rating the most. It’s a cost-benefit analysis; for a given development investment, seek the bigger benefits first. You can put effort into worker defense later, when it becomes a bottleneck skill.

Worker defense in Steamhammer (such as it is) had a bigger benefit than I expected, which means I likely put it in later than I should have. But Steamhammer was already an above-average bot by then, in the top third or quarter of the rankings. For a below-average bot, the benefit is probably small; you will lose most games to stronger opponents by being overrun with too many units because you didn’t keep up in macro, or by mismicro or misreaction due to missing skills. The basics are a better investment.

But as long as many bots are missing defense skills, other bots will exploit the missing skills. They’ll play worker rushes or whatever else is easy for them to code and more difficult, or not yet worth it, for their opponents to respond to.

As long as we have a steady stream of new bots, rushbots and other cheap exploits will make economic sense.