How a new game should look like

First we need to separeate versus and campaning.

In campaning mode you can lvl up your character , each lvl up unlocks a new weapon , you can use the new weapon to lvl up the weapon , each weapon has it's own attachmetns on it ,

For exemple you unlock the UZI , you play with the guy killing zombies etc to lvl up the gun , next upgrade on the gun is a flash light , next upgrade is a laser sight , next upgrade is incress rate of fire , next upgrade is a silencer. You can only equip just 2 attachems on the gun.

The weapons that we need to have:

Handguns:
Beretta 92f (this weapons is a standart 15 rounds gun low dmg 150 rounds reserve)
Desert Eagle (This weapon has high dmg 7 rounds gun can instant kill zombies 70 rounds reserve)
Revolver (this weapon has higher dmg 6 rounds can instant kill zombies and low HP special infected in 1 shot for ex: smoker , hunter , boomer , spiter. The weapons dmg is 250, 60 rounds reserve.
Glock18 (This is a low dmg automatic pistol 17 rounds in the magazin 170 rounds reserve)

T1 weapons :
MP5 (this is a low dmg weapon with 30 rounds)
MAC10 (this is a medium dmg weapon with 30 rounds higher weapon spred)
Pump Action shotgun (high dmg close range weapon with 6 rounds in the magazin)
Bolt action rifle (high dmg riffle with 10 rounds in the magazin)

T2 wepaons
M16 (low dmg 30 rounds weapon)
AK47 (high dmg 30 rounds weapon with high recoil)
Autoshotgun (6 rounds autoshotgun)
AutoSniper (20 rounds semiautomatic sniper)

T3 weapons special weapons
Grenade Luncher (high dmg 1 round in the magazin shots in an arc)
RPG (high dmg 1 round slow projectile shots straight)
Flame Thrower (high dmg has a fuel metter like a chain saw)
M60 (medium dmg can instant kill zombies 200 rounds)

Melee weapons suggestion:
The melee weapons needs to have something like a stamina metter.
Each hit drains your stamina, the more zombies you hit with your melee weapon the more stamina it drains.Ex:
Hiting the air 5% stamina
Hiting a Zombie 10% stamina
Hiting a Special Infected 30% stamina
Hitting a Tank 30% stamina
Stamina recharges fast if you don't hit for 5 sec it will start to fast recharge 2 extra seconds to full recharge your stamina metter.

Also you have a armory or a place where you can use your personal weapon in every safe room.
You can also get new skins etc to the weapons just like in CS and so on.
In campaning mode the free weapons that you can find on the ground has no attachmentes on them not even flashlights.Hand Guns no longer has infinite ammo.
Also the new skins can also replace the hole weapon for Exemple
You buy a new skin for M16 that turns the gun into G36 and so on.

How a new game should look like