The Concept
Pirate looters would be well, pirates, who happen to be looting. They would spawn on islands and 'patrol' while performing actions such as reading maps, digging to find treasure and occasionally find treasure. These pirates would be hostile to the player.
EDIT
(idea pulled from the comments)
Maybe it would be better if they were Privateers or Navy-men to make them more distinguishable from players - or simply have a distinct appearance whilst still being a pirate based enemy? I have always fancied fighting against faction navys in this game,
The Details
These groups would consist of, perhaps, 2 to 6 pirates who wield a variety of different weapons. These cutthroats would also attack players on sight. These could provide experience to the player in a trading company; perhaps a new one? The collected items could be trinkets as well as the spoils such as maps, resources and ammo.
These pirates would be far less common than skeletons but finding and defeating them will grant rewards which skeletons don't usually have to offer. They will also be more difficult to defeat than skeletons as they will be better in combat and more capable overall.
WHY SHOULD THEY BE ADDED?
I feel that adding these new enemies will make the world feel more diverse, alive and emergent as well as providing players with a new challenge throughout their play-time. These pirates could also be included in Athena voyages and may also be tied to commendations and skins.
I feel as though this would be a very welcome addition to the game. What do you guys think?
Thank for reading! please share and discuss your ideas in the comments!
