I think a must have that would make the game a lot better is being able to build bridges over water to connect land. It would make lots of things like the movement of land troops so versatile, and if you added the ability to build walls atop bridges to make a sort of tunnel without a roof, you'd be able to make very strong fortresses on island naval maps. I think a bridge variation for not every class could work as well, but most should have. Thats all.