I always thought that the signature quality the Sid Meier's Pirates! had was that "you are what you do".  At the beginning of a game of Pirates! you didn't choose a class.  You didn't say "I am a Pirate" or "I am a Mercenary".  You earned those class titles based on your actions.  I've imitated this aspect in my Pirate Dawn where "you are what you do" just like in Pirates.

The other good thing about making a pirate game is that there will always be an objective in any combat, which is far more important than anyone wants to see me described here.  I really could write a 20 page post here explaining the significance of that.  But, you don't even need to know all that, all of the positive aspects of that will just happen by themselves even if you don't know about them.  The fact that there is always an objective will just naturally make your ship combat work out a lot better than ship combat works in most other people's games.  Piracy perfectly corrects a serious issue with balancing combat between ships, and you don't even need to understand the hows or whys of it... it will just happen all by itself.  So, if you can make the tactical side of the ship combat fun, the strategic side of it will just work itself all on it's own due to the piracy aspects of the "scenario".  It will wind up working better than most other people's ship combat, and it will happen all on its own.  You don't even need to know about it for that to just happen all on its own.

Depending on where you want to aim on the game/realism spectrum:

• Racing. Pirate vessels have to be fast, racing is a good way to prove that.
• Hunting rare/mythical creatures (white whale, kraken, etc).
• Charting safe passages through natural hazards (reefs, whirlpools, hurricanes).

6 hours ago, suliman said:

I actually NEED a more explanation. What is automatic? In sids pirates I do think it suffered a bit from being TOO open. Just hunting ships quickly felt a bit empty, as you didnt really get much gold/cargo from it, and you could get the best ship (large frigate) 10 min into the game by just snatching it from a famous pirate.

I like this idea. Maybe i can look at assassins creed: black flag for a bit of whale hunting inspiration. I will not have mythical creatures but sort of an animal equivalent to "famous pirates" to hunt down would be fun.

Pirates is a very old game for having been an "open world", it could certainly be improved on today in many simple ways.  I was just pointing out the "you are what you do" aspect of it that so few other games have.

The fact that there is always an objective in a piracy game almost completely eliminates an issue that Star Fleet Battles players call "The Kaufman Retrograde".  This is one of those subjects that the experts can endlessly debate without ever arriving at a final answer.  The very short version is that a ship that is running away ("retrograding") is generally at a 3:1 advantage over the pursuer.  If the retrograder drops a mine, it is a weapon that is essentially "moving" towards the pursuer.  If the pursuer drops a mine it is simple left behind.  A missile fired by the retrograder has a double rate of closure, a missile fired by the pursuer has a long uphill climb to the target.  A retrograding ship can easily control the range.  It ultimately all has to do with speed, and the many advantages that a faster ship has. 

The retrograde causes more problems with game balance that I could even begin to go into here.  For example, a faster ship chooses when and where exchanges of fire will take place, and if it doesn't want to fight there won't be a fight.  If it wants to use that speed to grief and refuse to engage, for example, it can do that.  But an objective negates most aspects of the retrograde, especially issues like refusal too engage.  In piracy there is always an objective, so most of the retrograde issues just magically disappear when there is an objective.  You can't attack something by running away from it, you can't defend something by running away from it.  So many problems associated with the retrograde are not relevant with a piracy themes, these issues will correct themselves without you even needing to know that they exist.  It's the reason I've been saying for many years "most people should make piracy games, 'cause most people don't know enough about ship combat to make anything but piracy games".

That isn't meant to be insulting, it really is a very complex subject matter that a lot of very smart scientists, engineers, and real world military people have spent their lifetimes studying and still don't have a complete understanding of it. 

Like I said, it is a very complex subject.  WIthout knowing more about what you are doing, it is hard to provide specific suggestions.  You might get some ideas from the Pirate Dawn design document on my blog, it's piracy but in a sci-fi setting.  Feel free to use anything from it you want.  I won't ever get to make it, I know way too much about game and simulation design to ever be allowed to work in this business.