they could pretty much make a whole game of it, or at the very least a DLC. add more to it, like being able to board an enemy ship whenever you want (rather than only when the game lets you), putting together a fleet of ships and having larger scale battles with the ability to give commands to said ships, docking at a port and pillaging nearby towns (and blackmailing the town to give you money in exchange for not pillaging it anymore), etc.
theres a lot of things they could do, even tying it into AC. you could play as Connor's child or grandchild or whatever, and choose to either be sailor\privateer (good) or pirate (evil).
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