I suggest this a long time ago allready:
The idea is based on the mental state of the character. Living in a zombieapocalypse can drain your mental condition. Seeing friends die, get beaten or die by zeds, long time no good food, scrappy clothings,...
In PvP apocalypse you have to kill humans from time to time, this has massive impact on your mental condition.
1. killing a naked Lv.1 players makes your char feels like a a.hole and gives him pangs of remorse.
2. killing a players same or higher level has still decent noticeable impact.
3. when you get shot first then its always self-defence without any punishment.
So the player has to decide if its worth to kill another player based on his level he look like. You know you get the punishment anyway but ponder if its worth the loot.
The mental state couldt give buffs and debuffs over days/weeks, marking you as a killer and let other player hear your steps louder or at latest mark you on the minimap. There is a difference between just PvP players and pure Ego-Shooter players in this game. Some ppl shoot on everything thats moves and some think about if they kill or not, using ingame voice and such things.
As secondary and this is extreme important: Reduce the damage dealt from player to player by 75% or more. The fights are way to fast to give both players a chance, a reaction time, a chance to run away and flee or at least every players has to hit some more shots what brings skill into it. Even the Guns and Armor are more important and little differences can decide it after 15-20 hits.
The movement, the moment of reloading, the positioning and the aiming while evading hits,... that makes all no sense when the fight takes 1-3 seconds.
Players are like Heros in this game and zombies are just creeps. Fighting a player should always be a epic fight or least anyway a fight. Sometimes you loose everything you have to a death, this must be more worth.
Getting a headshot while standing still with open inventory is bllsht! Maybe give 50% damagereduction when your inventory is open, you are standing still anyway.
Raiding a base is a hard topic. In my opinion the base, the creative build of a player is untouchable but its a interesting part of the game wich is sadly not proper supported with more defenses, turrets and some alternatives to spikes and pits.
There are options:
low claimhealth: easy to raid everything
medium: the same like low but it takes some hours and many players have to much time.
high: it takes 1-2 complete reallife day with some mates hitting, hitting, hitting, repairing axe, hitting, hitting, hitting, repairing axe, hitting, hitting, hitting, repairing axe,.. this is no gameplay in my opinion and should not be supported by the game. Dont mislead players to do such things.
over high till untouchable: Deaktivates the raiding feature and take the PvP out to the streets/towns. Additionally you can take a rest from PvP in your base.
Baseraiding is nothing more than hitting endless amounts of time to blocks and doors. There is no gameplay included, no brain, no game, nothing, ... just hitting thousands over thousands of block hp down. Think about this pls, this is no gameplay! This is putting a weight on your left mousebutton and go afk or at least switch your brain off meanwhile raiding or it couldt be damaged eventually!