Navy Field is a game based on World War II warships of four countries: the United States, Japan, Germany, and Great Britain. With experience you can move up in ship type. It's interactive, as you battle players from around the world.
You start as a neutral with a frigate. Once you reach Level 12, you can choose a country. I'm now Level 18 Kriegsmarine, as the Germans have longer range guns.
The unrealistic thing about the game is that, in so narrowly focusing on ship construction, it overlooks advantages and disadvantages the actual WW II navies had.
In this Navy region, I thought many would enjoy Navy Field. Just one catch: it's a large (418 MB) download. http://www.navyfield.com