Introduction: (from the creator's site)
Battleships Forever is a freeware tactical Real Time Strategy game that put's you in command of a small fleet of warships in space. Combat and damage mechanics are extremely detailed. Everything is simulated in game if possible. There are no abitrary "to hit chance" values in Battleships Forever. The game also features many innovative mechanics that you've never seen before. For example, the Cronus Battleship sports a Flux Shield generator that allows you to draw a defensive force shield around your ships in any shape you want. Another example are the Deflector modules that are used extensively through the game. These modules make a single section of a ship totally invulnerable to fire. This means that you will have to manoeuvre your ships to attack sections of the enemy ships not protected by Deflectors while keeping your own protected sections facing the enemy. Position is paramount!
Players will command picked fleets made up of Battleships, Destroyers and Patrol Craft. The completed game will include ten campaign missions and multiple skirmish modes.
Battleships Forever is inspired by and loosely based on Warning Forever by Hikoza.T.Ohkubo
Screenshots:

The Flux Projector in action. It projects a shield that you can draw as you please that stops bullets!

Pew pew laser beams!

Boom!
Game Modes: (from Game Hippo)
There is a campaign mode with several missions, but also contains several modes. In Sandbox, you can freely spawn units and set up a battle to test things out. In Raid, you play the part of Pirates who must terrorize the local Shipping Lanes.In Blockade, you are defending a convoy. In Grinder, you battle ever stronger waves of foes. And Finally, in Leviathan, you must take down a titanic battle station.
Here's the best part: You can create your OWN SHIPS with an editor. Thats HOT SHIT right there!
More Info: http://www.wyrdysm.com/games.php
Download Link: http://www.wyrdysm.com/bfdownload.php
Um, words do not describe just how well made and awesome this game is, and its in beta. It is quite simply one of THE best Game Maker games I have played, and one of the best freeware RTS' ever, in my honest opinion. Everything is intuitive and well crafted, and there is an amazing layer of strategy and complexity to be found.
My only complaint is no multiplayer/online modes. :/