Starcraft AI blog

Hao Pan’s zerg variant of his terran bot Halo, Fresh Meat, is also back. Fresh Meat’s big claim to fame is that it uses COEP for production decisions. I wrote up COEP in 2019, where Hao Pan left a comment about the Fresh Meat version of that time.

COEP is a search method. Like any search method, it relies on you to provide a game model (the “forward model”) to answer the question “what happens if I do this?” and an evaluation function (a “fitness function”), to answer “and is it any good?” Results are shaped by the method, but depend mostly on the model and the evaluator you provide: A search method amplifies the smarts of its model and evaluator by using them to look into the future, but you need to provide those smarts in the first place, as a seed for the search to plant. (In COEP the seed grows into a lawn rather than a tree, but whatever!)

I was not impressed with Fresh Meat’s production decisions. It likes an early spawning pool—sometimes 4 pool, 5 pool, 7 pool, sometimes later—and makes early zerglings when it feels like it, or not when it doesn’t. It likes drones and sunkens. I haven’t seen it visibly react to enemy air units. It often lets its minerals run up to a high level, a very bad sign. I’m speculating, but the play is similar to what I’d expect if the model and evaluator were trained by play against the built-in AI. Could that be it? If so, perhaps it is learning on the ladders and will improve over time.