Sorry for posting in an old topic. Anyway, wouldn't it be easier to make the two difficulties (recruit and Regular) have the options to stop player's from shooting one another. In recruit player's are not able to shoot one another and in regular the option can be tuggled on or off when setting the options for his/her server. I would expext these to be very popular servers aswell because so many people play in private sessions where they don't need to worry about player killers aka player bandits, those who like the challenge of trying to avoid player's aswell as zombies could then choose a server with a higher difficulty setting (in which case the option to stop player's from killing one another can't be turned on).