First of all, I love this game and I have a lot of fun playing it and these are a few suggestions that in my opinion would improve the game a lot.

-A new small slot in the inventory only for the cards/keys, I really don`t like having to throw a shotgun because I have to pick up a little key or card, if it is something like a fire extinguisher or the bolt cutter I totally agree, but no with some little item.

-Pushback to the shots, everytime I shoot a zombie and is not in the head the zombie will continue rushing me like nothing, would be nice to make the zombies stumble a little depending of which gun shot it.

-Footsteps sounds to the zombies, they are absolute silent and would rush running to you and make absolute no sound of footsteps, giving you some bad times.

-Decrease the sound of the zombie scream, you can hear it miles away and never will help you to detect where the zombie is exactly, it gets a bit repetitive after a while.

-Some maps could have few spawns of random enemy survivors that will shoot and attack the players and the zombies, just like the police station map that you have the prisoners, but the prisoners repeat the same voice lines over and over and gets really annoying.

-In some indoors sections would be cool to have random blackouts, it would increase the tension and add a little more of difficulty.

-Have the zombies break some walls or vents and make a loud scream when the player is close, to give some kind of jumpscare.

I absolutely understand that all of this is easy to say and hard to make, but these are some suggestions that would improve a lot the game experience in my opinion.

Shoutout to the devs for adding split-screen multiplayer to such an awesome game :)