Oh boy, they really don't have to be smart to be agents.
New mine attack modes are in. Each mine runs simple rules: maintain orbit distance, match neighbors' speed, snap at anything hostile within range, return to formation.
The result? Swirling flocks that look almost intelligent. Mostly they stay in their orbit, occasionally darting out to bite an enemy, then lazily drifting back into place.
No navmesh. No behavior trees. Just physics + a handful of impulses.