It was a while ago now, but I suspect we all remember Air Bucanneers, and the discussions around a pirate/steam-punk game that could come off it.
Seems like in teh next year there may be three, all with different takes on the concept.
Skull and Bones
This is an offshoot from Assassins Creed:Black Flag. IT looks like, to all intents and purposes, you play as the ship, rather than an individual onboard a ship. The combat, and sailing, however, looks pretty sweet...you can see wind direction on the mini-map, and there is ramming, broadsides and boarding. From what I've seen, this is the best-looking of the games...it differs to Air Bucanneers in that you control the entire ship, rather than being part of a team...however it looks like there will be PvP and Co-op, with fleet battles.
Sea of Thieves
This one looks more like an adventure game, though it's supposed to have naval combat in there as well, which could be interesting, as you play the pirate, not the ship. This one has the potential to have combat more like Air Bucanneers, where co-ordination on-board is key...however it could also suffer the downside to that in that small player numbers could be an issue, especially if thereis little/no AI support, or crap-bot-syndrome (I'm looking at you Battlefield 1942).
now this one is a bit left-field...it's touted as "FTL meets Pirates", and is being developer by a single guy. FTL is probably one of my favourite games, hits a real sweet-spot between turn-based, real-time and complexity/time commitment for me. Here it looks like rather than controlling the ship in combat, it's about worker allocation as you direct the crew to manage the actions. There is also an open-world map that screams Sid Meiers Pirates! (which was also a good laugh, even if it was a series of dancing mini-games, and weird noble-women who blinked one eye at a time...)
I think the combat in Skull and Bones looks the best, which is to be expected really, with a big developer like Ubisoft behind it, and I love the idea of massive naval battles (I once terrorised a big wargame of naval combat, after being given control of a small escort ship and immediately heading off solo into enemy lines, rather than the beautiful formation sailing everyone else was intent on...obviously I died, but I caused enough confusion in the enemy ranks that the rest of our fleet were able to fragment and destroy them...). That said, I have a feeling that Abandno Ship, if done well, could be amazingly addictive.