The Unity Navmesh system is good, but say you want your NPC's to avoid monsters/enemies and not run past them. There is a dynamic obstacle avoidance element but you cannot put it on a monster using the navmesh agent as the monster would try and avoid itself. Or you end up with a monster afraid of it's own shadow and erratic behaviour. Is there a way around this conundrum, as I'm just surprised the rather good navmesh system does not have an easy way to add predator/prey behaviour. Also it could use a layer or matrix system for neutral, attract, avoid. Which should work in most games. It would allow the construction of biomes with competing fauna a flora a relative doddle or just plain fun. Build an island of competing critters and plant life and just see what happens.