Dont' worry, in the same tradition as ns_desolate, there will be eastereggs
Regardless, it has been settled that I'll be making a luxury submarine, which will allow some pretty interesting architechture. It won't be as long as HMSRedrum, but will consist of three or four decks. I spent nearly all day tracking down and creating textures - I now have a very hefty, very comprehensive texture base to work with.
Here's a very out-of-date screen. As you can see I'm going away from the cartoony cell-shaded look and into a more somber tone - Personally I don't think that cartoony look really fits the nature of the game, at least in its present form.
Regardless, there will be plenty of places from which you can ambush, hide, and make your way around the submarine. This shot is from Deck 2, which features a Restaurant (behind the wall on my right), Bank, 3 Cabins, and Restrooms. Towards the front (behind the glass doors) will be a grand staircase.