Love the game so far, been playing mostly for the PVE. Love the areas, the levels all have interesting designs and tunnels. the zombie swarm concept is very insane. I like how there isn't too many types of zombies, but just enough to make things interesting. Currently doing insane mode now with 2-3 players and a bot. I'm sure devs know what needs fixed early so I'll talk about things that would make the game better for the future. I really like the game and don't want to get bored of it. (sometimes playing through slow even)
Introduce vehicles to sit in, even if the vehicles drive themselves. Tanks/Jeeps/Helicopters.
More interesting zombie traps. Spike walls, trip wire,
More classes with support abilities. Placing walls-(Carpenter) Sound distraction-(DJ) Oil slicks-(Mechanic) Adding in Auto Turret and turret drop skill. Flares.
Have some very dark areas that require flashlights.
Introduce zombie animals? Where are the dogs and cats?
Add some more large killing mechanics, every big wave has the same mow down strategy. Add a vehicle to gas push down waves? Helicopter blades to turn on, Big walls of fire, Demo a building to fall on zombies.
Instead of a menu lobby, make it an in game lobby where you are in a foothold somewhere in the world, testing guns on distant zombies. but leave the area safe. Giving the players a much better sense of constant struggle and survival.
More PVE modes= Time survival, Tower defence mode, (City Survival- large city, open world, discover players and bots to help you, build defences. This is much like the starcraft 2 zombie custom gametype.)
For PVE let a random player join to play as a zombie for if games are full, opt in style.
PVP modes = Maybe a battle royale with survival? look what that did for Fortnite as it was a zombie game at first.
Active Zombie kill score somewhere on the screen.
Badges for difficulty completion/achievements