Best idea in the thread so far imo. Would discourage prolonged pvp in towns/airfields or camping in vantage points over towns for long periods of time, as well as add some spice to pvp in previously safe locations. Could potentially turn locations into deathtraps. I think this mechanic should only apply to the 'louder' weapons, so everything bar most pistols/silenced weapons/crowbar/axe. In addition to this, I think having zombies spawn out of thin air when you fire a loud gun needs to go. Firing a loud gun should definitely attract already-spawned nearby zombies, but having it swarm you with 20+ frenzied zombies in a field that quite clearly did not contain 20 zombies (or you wouldn't have shot your gun in the first place) is a very counterintuitive and punishing mechanic. These two changes would be a good direction, I think.