There is another interesting project - WarThunder (
http://www.warthunder.com). At this moment this game is focused to the planes, but at the future the developers plan to add fleet units.
Some core ideas which may suggest submarine simulation available in the future:
- There are some modes, and one of them is a 'simulation' (FRB) with limited ammo, view, physics model where player should control some features to avoid self-destroying,
- Long time missions (for human controlled planes is 1 hour), or not limited time mission against AI,
- Destroyers are "a light warship designed mostly to fight against enemy submarines and aircraft",
Hope dies last?
No more detailed info at all.