UPDATE 6/23, 12:38 EST: Okay, so we've gone in and made the game easier, and fixed a few minor issue. Those with Flash Player 10 should now be able to view the game properly.
Requires Flash player 184.108.40.206 or greater. If you don't have it, get it now.
In case you folks don't want to read our enthralling How To Play instructions in the game, I'll give you some simple instructions here:
Erect towers and structures by clicking to select them from the menu and clicking to place them on the field.
You can place multiple of the same tower or structure without re-selecting it from the menu by holding the shift key.
There are three level types: Kill all Enemies, Erect a Landmark, and Survive. Pay attention to the objectives, so you don't get chumpitized.