How about we have factions in the game, here are some examples:
Faction less: Just joined the game or wants to be a lone wolf
The church: extremely religious, relies on faith and speed. Mission: to increase their numbers
Has access to faith stat (operates like luck)
The Militiamen: extremely unbiased, relies on liberty and strength
Mission: to provide protection to civilians and hold courts
Has access to liberty stat (operates like intelligence)
The mercs: extremely honorable, relies on accuracy and strength by numbers. They are mercenaries, assassins and personal bodyguards
Mission: to have more members and to do the dirty jobs
Has access to accuracy stat (makes it more likely to get a hit with a weapon)
Survivalists: extremely healthy, relies on hiding and sticking together.
Mission: to survive
Has access to survivalist stat (improves health recovery)
Scientists; extremely intelligent, relies on said intelligence and bio weapons.
Mission: to find a cure for the virus
Has access to chemistry (allows then to craft bio weapons or upgrade other weapons)