My idea for a pirate game would be like an online co-op. If you were placed on a pirate ship with random people people, would you be able to cooperate? Would a better player take advantage of his/her shipmates? Would everyone be better off if they could just start a pirate ship with their friends? I think placing random players on a ship together and telling them to do whatever the think a pirate does would be interesting. Who would become captain? Would they form an armada with more ships? Would everyone on the ship fight? There's alot more questions to be asked, because my idea really isn't fully developed. But I was picturing a massive online ocean with various different ships either competing against eachother or joining together. Hopefully it wouldn't be like an MMO were the only class is pirate because that would suck.

You've pretty much given an exact description of Puzzle Pirates.

Like I said this really isn't a fully developed idea. But oh well.