I have an idea about animal migrations. Spawn of animals is quite big so there is enough animals to create “a horde” of deers, birds, wolves, fish, moose etc. Their “horde” should work as a horde of zombies: they gather next to a given forest/ field which depends on animals population. Their migration may be a great hunting opportunity but on the other hand, migrations may be dangerous. Our vehicles may be destroyed by a lot of moose when they don’t see other way to pass our vehicles. And of course wolves and other predators should attack us when we are too close. Hordes should be fast in order to avoid ants, zombies and other monsters.