so an idea i had

the zombie outbreak had come and there is a well armed mc in the city fending off the undead horde trying to stand ground.

so you can do two things with this as you engage them in this world.
one attack them and illiminate them. two you can make them join your base.
this event can be all over the map at a random point. so the idea behind it is that you need to think fast before they are overrun.
take it they can last in the first two days if luck strikes the table

if you choose to kill them to gain recources and money they will attack you with all they have.

now on to helping them will result them joining you this will set an event in wich you need to get one of them to your base safely.
in doing so you gain more. vehicles. units. and defences.
failing in doing so will result in a loss of all of the above mentioned benefits and will cause them to turn hostile.

this is one faction but the same can go for

police
swat
riot
militia
civilians

i just like motorcycle clubs more

sorry for the spelling btw