A clone?
There are countless games with this concept. Sid Meier's Pirates, Port Royale, Pirates of the Carribean, Age of Pirates, Tropico(To some extend), countless MMOs where you command a ship and sail the high seas and that is probably not all.
A lot of players were longing for this, two of my friends included, who said Mount & Blade would be perfect if it was a pirate game.
