Snowbird Games, creators of Mount and Blade: With Fire and Sword, have announced their upcoming project, Caribbean, that brings many of the mechanics of M&B to a 16th-century swashbuckling setting. The Mount and Blade series is definitely in that "high investment, high reward" category that only really works on the PC (with the likes of EVE, Dwarf Fortress, and Day Z). It's also about as close as you can get to a full-blown Game of Thrones RTS.
If commanding hundreds of scallywags in real-time boarding missions interests you, read on.
Snowbird's announcement cites a trove of ambitious features, including:
Sea battles with intuitive and easy control system;
The real-time boarding fights that throw player in the centre of the action;
Detailed management and customization of both the fleet and the crew;
Complex siege system allowing the players to storm forts, harbors or entire cities;
Different kinds of artillery: shipboard cannons, mortars and howitzers;
Random events system that keeps players question their decisions during their voyage;
True ‘Carribean’ atmosphere of the vast and dangerous world;
Unique NPCs whose design based on the real historical figures;
Various multiplayer modes featuring the sea and land battles, boarding and sieges.
The devs say you should be able to get your hands on the buccaneering goodness this September.