Once had an idea for a PS1 common pool TD, called the Vanquish.
But of course that's the old PlanetSide style and leitmotive.
Just now was doodling a bit and just made some basic PS2 TD concepts with different configurations and principles that at least somewhat fit the new art direction (mind, these are just napkin size 10 min. doodles). (click images for bigger size).
http://i211.photobucket.com/albums/b...D_Concepts.jpg
Then something hit me: the driver/gunner debate.
What if...
Heavy tanks: gunner main gun / driver secondary gun
Tank Destroyers: driver main gun / gunner secondary gun
Then the advantage of the gunner is at all times 360º weaponry.