http://store.steampowered.com/app/293010/This is a Steam game in the Alpha phase, which sells for $15.
'Caribbean!' is a sandbox pirate RPG with a larger focus on battles (both on land and in the sea) and management of player's character and his crew. I've played over a hundred hours and I figure it's time to write a review. Apparently it has the same base programming as Warband Napoleon Mount and Blade. I never heard of that, I just have an interest in "Age of Sail" games. Well, all naval stuff.
The closest thing to this I have ever played in terms of controls & visuals is probably Total War, in terms of subject matter, Sid's Pirates!
Compared to Pirates!, This game has a more developed economic system. You could play as a merchant. I like to play as a privateer/pirate hunter, but it's open ended. At the moment, things are unbalanced and I need to be a merchant in order to support my predatory practices. As it is by the time you have replaced your dead crew and repaired your ship(s), you lose money taking anything but smugglers.
Better to play with cheats enabled at this time, which seems to put boxes of jewels aboard the smugglers more often, allowing you to buy cool equipment, and ship upgrades. At the moment don't upgrade your flagship. There's a bug that makes the infirmary, particularly , disappear. Some of your guns go with it.
The instructions are inadequate at this time. Pathfinding can't be trusted. Your ship is likely to dock on the near side of an island and travel overland by horseback to your destination. Trouble is, if the shortcut puts you in the lap of an enemy who happens to be besieging that port, or if the port has gone to war with your faction, you can easily be obliterated or imprisoned. Game over, essentially.
You have to play with sound off to avoid crashes. It's not easy to learn. I wouldn't recommend buying it until the next update. Currently it's version 0.802
But in spite of all of that, it's fun.
I like shooting the blackpowder pistols and muskets, with their delayed ( half or 3/4s of a second?) fire and obscuring smoke, and the time consuming reload. It's an interesting challenge to shoot the enemy before he shoots you. You can throw knives, toss grenades on the gangway, or fence, too. There are sea battles between multiple ships, and you can blow them out of the water, but boarding and capture is more profitable. Get too greedy and spread yourself too thin with prize crews, and next thing you know you'll lose your flagship.