How about a fantasy RPG set around the 16th century in English countrysides?
Seriously though, I've always loved the idea of a Pirate-based RPG, you start in a little port on the ass-end of nowhere, doing odd-jobs for petty criminals, then stowaway on a pirate ship after a job goes wrong. The crew discover you and force you to work, then the ship is attacked. You help fight off the enemy, and they make you an official part of the crew. You then go on raiding-parties, quests for treasure, etc, earning currency (I'm thinking Doubloons) dependent on how well you did and if you followed a secondary objective or not.
After a certain number of adventures you are dropped off at a Port town for a few days. Here you can buy new clothes (I'm thinking on the level of Saint's Row, customization wise) and upgrade your weaponry and such. You'll do a few of these stops until something happens later in the game which makes you Captain of the ship, letting you decide the destination and missions, and eventually you'll build a fleet, able to send different ships off to missions (with a chance of failure) for a monetary reward, as well as some special items. Think Assassins Creed Brotherhood.
Though, all this is just a pipe-dream with current technology, as what I'm thinking isn't exactly realistic and involves swinging across to the enemies ship, chopping them all in half then swinging back, dynamically.