Build your own robot army
Small drones to towering automatons, and the rules that keep them useful instead of wandering off.
Turrets are only one way to hold the line. Your factory can also build robots, from small scouts and drones up to the Heavy, the Turret walker, the Artillery and the Titan.
Space, not just cost
Each fabricator holds 12 units of robot. Scouts and drones take one or two, the Heavy takes four, the Turret walker and the Artillery take six, and the Titan takes the whole twelve. So you choose between a swarm and a single giant.
A leash, so they do not wander
Robots only go after enemies within 30 tiles of the fabricator that built them, or of the core. They always fight anything within 9 tiles, and they march to help anywhere inside the leash. Idle ones stand guard just outside your base.
The big ones plan their routes to keep a tile clear of obstacles. A robot walled into a pocket gets lifted out after about three seconds, because nothing is worse than a Titan stuck behind a fence you built.