How about this 'Western' idea:
1) Place wallboards to a number of cities (preferably cities people usually do not check)
2) The wallboards contain 'WANTED' posters. Reading it gives you a list of BANDITS that have recently killed survivors or hero's and some info that rufly indicates some information where he WAS a lot of times in the past.
3) When the bountry hunter kills the person, he gets his payment in some random goods, like Guns / screws/ whatever.
4) extra: The hunted will be able to to remove his WANTED posters from the boards, giving him a chance to get away with what he did.
Imho:
- A bounty system will make some people reconcider playing this game the easiest way; KOS everyone
- There will be new POI's, causing people to meet up / run into eachother
Lemme know what you think
