Just a few things I’d like to see in the new version;
zombies that can fall down heights - having stairs to head up is great, but they’re zombies; they should see going straight down as the optimal route. In addition to that, while they don’t take fall damage, it’d be cool to see them ragdoll on impact, and then get back up.
This would also be cool as an idle, having some zombies ragdolled to start, making the player think another person is around, only for them to stand up and start lurching towards them.
Buildable Pathfinding; perhaps a simple way point is added to every significant part, doors, stairs and walls, meaning zombies will no longer just see the ground floor of a base.
Large-scale Nav mesh; I think you’ve already been talking about wanting to do this, have a mesh that goes the size of the map, rather than just the cities. I think that would be an awesome idea. Go into a town to get some supplies, drive away with some zombies following you. After a short time back at your base, you suddenly have 20 zombies at your door. This would also be great for some pvp possibilities, using them to your advantage.
An infectious camoflauge; Much like in the walking dead, I think there should be a way to camoflauge yourself from the zombies. It would act as a higher level sneak skill, but slowly infect the player over time. It would also dissapear if the player was outside during the rain.
Lastly; with the addition of a large-scale Nav mesh, Bandits. This would perhaps make solo a little more engaging, but has possibilities for Multiplayer too. A bandit could spawn by themselves or in a small group, and start building structures around the game world. They could try and be friendly, attack or ignore you (If you’re in camoflague perhaps). Maybe even follow you to your base and attempt raiding it. It’d take some work, but it would be so worth it. (Failing that, access to the NPC api, so we can make custom zombies/NPCs with unique states/conditions)