Koopa Road in Mario 64.
Now about battle damage showing on the ships and oil slicks... +1. The listing of the CA and DD's, could be done easy vs the listing on the CV. You don't launch or land planes on a listing CV. Holes in the deck of the ships would also be nice, but you'll find it hard to launch and land with holes in the way.
For the CA and DD's, Listing would take place when you get a bomb hitting JUST next to the ship and/or if it get's hit by a torpedo. The hole in the hull/deck would show with a torpedo impact or a bomb hit. Something along those lines?
The CV will be a doozy. The hole in it's hull/deck won't be too much of a problem. Example: At 1K, you see a hole. At 2k, you see two, etc, etc. At 4k you start to see smoke and at 6-7k, you will see the fire. Listing issue though, may get a lot of flak if they decided to go with that on the CV. Primarily because you'll have those people who don't pay attention and up only to watch their planes slide over the side and/or hit the tower on takeoff. If they decide to prevent the list from affecting the orientation of your plane when you take off, they would have to reprogram the CV so that your plane won't hit the tower when she's listing. Listing on the CV sounds like a coding NIGHTMARE. Maybe if she's hit to where she'll list, you can't up from then CV for X amount of minutes? (Counter flooding and what-not to lever her off) You won't have to worry about the listing when it comes to the guns. It's like being up on some of these steep hills in a tank. Just got to adjust your aim accordingly.
Which brings up a question, as they take damage, would their speed decrease? I didn't see you mention whether the damage would affect the ship's speed or not. If the ships list, their speed is affected.
Of it all, I think the oil slick would probably be the easiest to code in and implement.
Another question is, why limit to just the ships? We could do this with hangers too. Maybe have the hanger showing a few holes in it and/or some smoke. Example: At 1K damage, the Hanger shows a hole/s in the roof. At 2k damage, you have the hole/s and some smoke.
