Also, should come with two saves. One "get-to-the-safe-house" build and the other for waves.
Your late bro.
Gun shots may or may not alert zombies.
Zombies should have groaning and moaning sounds.
Something like a pipebomb. I was thinking a steak that you could throw to lure zombies somewhere else. And you could right click to eat it for health.
Now, we should have at least some different zombies. Maybe rarely a zombie will spawn that is faster than other zombies and when it see survivors it will start screaming alerting other zombies. And bigger zombies (not a tank though) that have more health, do more damage, but is slower.