I know I'm not the first guy to think about it, but it crossed my mind while I was watching some footage I've recorded and saw my friend and myself kinda get stranded on an Island, as I (voluntarily) forgot to lower the anchor before going ashore.
Now I literally have no idea how hard or how easy it would be to implement, but I think the game could be like 10 times better (for me at least), if you could just play Liar's Dice literally anywhere, on your ship, on an island, of course in the taverns and gamble your hard earned gold.
Other games would be cool too, but I really feel liar's dice would be the number 1 game to consider. The setting is perfect for it (not that I would know, I only saw it once in Pirates of The Carribean), and it was one of my favorite thing to do in Red Dead Redemption (though I missed out on playing it online).
(And yes, I know all about the mermaid and back to ship mechanic, I just thought it would be really nice to have something really fun to do when you don't feel like doing quests, fighting, sailing, and stuff like that. Some nice thing when you want to take a break without going AFK or quitting the game)
