Starcraft AI blog

I like CerkoBot by Tomas Cere. Its play is complicated and interesting and entertaining. One bit I especially like is its way of defending its choke: It will chase harassing enemies away, but only up to a limit—it maintains a frontier beyond which it doesn’t stray while defending. Though it’s old, it still puts up a stiff fight against many new bots.

But being old, it has a lot of weaknesses. It’s hardly fair to criticize a bot which hasn’t been updated since 2012, but I’ll catalog the big weaknesses anyway. I must be cruel at heart (but there’s a method to my meanness).

• Its early build order is not safe and it often loses to rushes.

• Reavers are its backbone, but it has poor reaver targeting and doesn’t understand how to position other units to avoid blocking reaver shots. A reaver that is in range of an enemy building will never move forward to target units, no matter how urgent. (Luckily for CerkoBot, reavers are so strong that they often turn the tide anyway.)

• It sucks at keeping its army together. When fast-moving units encounter opposition, they often have to retreat because the reavers have been left behind. That’s only right, but instead of gathering the army at an intermediate point, CerkoBot retreats the distant reavers too, staying scattered. Learn from vector units, they have both scatter and gather!

• It mispositions its observers so that it sometimes has no detection at critical points. It also bunches them together, often losing them all at once.

• In the late game it builds arbiters, but it can’t use them efficiently. It loses them too easily, doesn’t maneuver well to cloak more units, and never uses stasis or recall.

• It can’t cope with a spider mine blocking an expansion spot. I think that’s the main reason that it loses to IceBot.

• It dies against mutalisks.

• Like many bots, it hasn’t bothered to read the victory conditions and wants to fight the enemy’s army instead of the enemy’s bases. (Except the reavers, which shoot buildings over workers.) It will ignore an undefended expansion to lose its army against an entrenched terran formation elsewhere.

If CerkoBot were ever to become a contender again, as it was in its heyday, it would have to fix a bunch of these weaknesses. Eh, probably more. Why not clean the Augean stables instead? That’s why we need starter bots on the one hand (Peneus), and search and learning tech on the other (Alpheus).