Very nice simulation. In many many pursuit, a key question is whether the pursuers are able to coordinate in any fashion. It is clearly not optimal for each pursuer to just aim towards the nearest pursuee. "Zombies" aren't going to coordinate, but "cops" can and do. Coordinated "cops" should steer toward areas other cops aren't able to cover. Then there is "leading" the pursued rather than aiming toward where they are now. It is a harder problem and there are multiple possible "strategies" for coordinated pursuit. I am just throwing this out there for those interested in taking this sort of model further.