Real-time combat in the Age of Sail (covers 1775 to 1820), where 'real-time' means waiting for your ship to maneuver, and your cannons to reload. The default time scale is for double actual time, though it can be sped up further, or slowed down to actual time.
It is a serious look at naval combat, with stats for (according to the publisher) over 2000 ships, rated for cannons, crew and rigging. The major limitation of the game is obvious: there are only 8 facings. You can command a ship to turn, but it takes time to do, and will have no effect until a 45-degree turn is accomplished. Otherwise, movement and firing is well-handled.
One hundred scenarios range from single ship actions to the Battle of Trafalgar, and a scenario editor allows the creation of whatever is desired.