Bloody Pirates is quite a good game, where six teams of two battle it out over the 18th century caribbean. Three team modes, with 6v6, 4v4v4, and 2v2v2v2v2v2
Board rival player players, or NPCs ships and battle with your captain and crew to take their ship - steal their gold - , and choose to sink it or use it.
Do they have too many crewmen? Then kill their crew from afar with your cannons! or perhaps you can sink their ship from afar, but which gives only a bounty from your country.
Destroy, pilage, or take ports over! if your strugling to find crew, why dont you bribe it?
Random Events are often, and give a fair amount of gold, the same with quests from merchants, while economic quests from your own nation help to upgrade your ships (current and future)
Goal can change
Read F9 and ingame help for more
It is quite old but still good, kind of like Metastasis and Cruiser Command