We've been playing this game for quite a while and I'm going from memory on some of the rules, so forgive me if I omit some stuff. This is a game that was release in the early 90's and was a very abstract reflection of the Naval situation at the time. It was basically NATO vs. the Soviet Union with the ship cards giving relative strengths.
To start the game each player is given a certain number of ships (in one of the optional rules this modified somewhat where each player is given a certain number of destroyers, cruisers, a carrier and a submarine). Since NATO and Soviet ships aren't balanced, this could lead to a fairly unbalanced mix of ships (US Carriers kick ass....Soviet Carriers don't...I'll talk about that a little later). Your ships are arranged into rows. The first row is typically your low value ships. Your middle row is your higher value ships. Your last row is typically your carrier.
A turn consists of rolling the die to determine the number of actions you get that turn and then performing those actions. If you have an additional ship, play before your take your turn. Same with damage control and retreat. Then you can discard as many cards you want and finally draw your hand up to seven (or eight...I forget which). You can also re-adjust your fleet by moving one ship (I forget if you can move more) but this is at the beginning of your turn.
An action can be one of the following actions:
1. An attack. In order to make an attack, one of your ships must have that type of card and you can only make 1 attack per type of launcher on your ship. Guns can only go from the first row and attack the first row of an opponents ships. Missiles can go from either the first row or second row and attack either the first or second row. An airstrike from a carrier can hit any row. There are defenses against each attack.
2. Place an area defense. Area defenses cover your whole fleet until the beginning of your next turn.
3. Perform an air strike (if you have a carrier or a card)
4. ASW - If you have the card.
To defend against an attack, there are defensive cards that you can play from your hand (or if you put up an area defense, they cover your whole fleet). ECM works against missiles. Evade works against guns. I forget what works against planes.
Carriers allow you to make an airstrike, and it's either based on the airstrike rating if you have the first set or the card that comes with the carrier in the later sets. Attacks made on the first row are more likely to succeed. I forget how the airstrike rating works, but if I remember correctly, you get +1 on attacks make to the first row and -1 to attacks made to the back row. If the airstrike hits, the ship is sunk (unless it's a capital ship, in which case it's crippled).
Overall, I think this is a pretty fun game. It's in the same vein as Avalon Hill's Naval War but a little more complicated. It gets even more complicated as you add the other sets. One of the other sets has a provision for playing a campaign game. The other set gives you tactics and potentially bad luck events. I think the biggest complaint about this game is the imbalance if one person gets an American carrier and someone else gets one of the Soviet "carriers".
Some of the cards give bonuses and have different effects. For instance there is a landbased bomber card that can be devastating in conjunction with a surprise attack. There are rules for the additional ship, that if you have a poor fog of war roll, you can get a better ship.