Well my idea was this really we could fuse the two ideas together so sort of like an rpg gang type thing where you can either be in a gang or not gangs pretty much fight for turf and try and rule the islands i was thinking of having 3 main gangs each with one island and then of course the police the gangs are all trying to take over eachothers islands and trying to get as many zones in their name if you can see what im saying. Each zone that they take can have a value so if there are shops and somone (maybe a normal person who doesnt want to be in a gang yet) buys from the shop then the gang get more money to spend on faster vehicles or better weapons
of course as i said you dont have to be in a gang you could be a honest citizen and pretty much play rpg style and try and make a honest living by having a job like a pizza boy or a mechanic and thats how you get money (or maybe having things like pay days every day you get payed for your job)
then you could have your dishonest citzens who side with the gangs but arnt really employed by them these people could be drug smugglers or even people like materials dealers (in other words gun smugglers), these people could sell these stuff to gangs and therefore make that gng more powerful
There could also be lawyers as well as if one of the gang members gets put in jail (maybe jail time could be 1H normal time or longer depending on what crime they have done, so that people are pushed into using lawyers) they could reduce the centence time or even get them out of the crime they have done, for a fee of course.
and then we have the police there could be certain tiers(police could be called with phones which players can buy from stores) :
Normal petrol cops: they are the first tier standard cops they respond to minor disputes and shootouts
Swat: they respond to gang wars that are happening in an area or zone
FBI: they respond to normally 2 or more areas or zones that are being taken over by gangs
of course there could be corrupt cops such as they let some gang members go for a small payment.
there are more things to clear up of course like what jobs there are for the non gang members but thats my idea so far ask any questions about it if you want and i will answer them