I took a different approach to the theme, instead of the game being focused on one tower, the game is focused on multiple lighthouses, which I guess can be considered to be towers.
Use WASD to move.
You have AI teammates, but by pressing E or Q you can control them one at a time.
Press left shift or space to fire your cannons and destroy enemy ships.
Go near a lighthouse to conquer it.
Also sorry about the horrendous music :D