Really cool concept, pretty good execution. If you ever played Intra Galactic Battles on your 386, this is like that but with boats. So I guess that makes it a bit like Starfleet Battles.
It's like Gratuitous Space Battles (love that game still), but you have direct control over each ship, and you generally only have a fleet big enough for a few ships at a time.
So before the mission, you choose hulls and equipment for every ship in your fleet, based on a predetermined total "fleet value," which I imagine is calculated based on the difficulty of the mission in question. Then you micro-manage your fleet in a turn-based battle.
You issue move and targetting orders per ship, or if you're really a micromanager, you issue fire orders per weapon.
Cool concept, right? Well I'm happy to say that this game pullis it off smashingly. The interface takes a bit of getting used to, but the tutorial is actually VERY good. Only once did I find myself thinking "okay... How do I do that again?" It's very intuitive, and the missions are varied and overall the game is just fun.
I give Leviathan Warships an A-. Really neat concept, nearly flawless interface, and just plain fun.