One thing that struck me as a better idea is to adapt some of the missions from the game Super Battleship back on the SNES.
Start the movie with that annoying escort mission where a severely damaged ship has to navigate through a minefield to safety and is pursued by subs. Let the ship sink (as opposed to making it to safety) and spark a war between opposing navies. Then cherry pick from the remaining missions for different skirmishes culminating with the game's final mission, "Total War", which was a slugfest between every ship on hand for both sides. Granted, this game left off aircraft carriers for action purposes (i.e., no big guns to be used by the player), but working them in would be very easy to pull off in a movie.
For character focuses, choose a cocky rookie officer who has the cliched sibling/relative/parent who went down with the damaged ship as the main lead and place him in charge of a new task force. Have Liam Neeson be the admiral in charge of the entire fleet who is still uneasy of letting this new officer take a big command. Let the rookie bond with his crew and grow as a person through trial and error and a few embarrassing defeats. Then, develop the enemy fleet. Let them have depth and complexity as opposed to the one-note villains most action movies receive. At the final battle, let both the main lead and the enemy leader have one of those standoffs that are pure action fests that go down to the wire, with both accepting the other as a worthy opponent before the enemy ultimately loses.
There, I've made a better movie idea than what Hollywood has come up with in under 10 minutes. And one that is true to the nature of the original board game to boot.
