theres a delay in the correct word being removed, making me miss the first letter of the following word... Plus i'm sure i've played something similar. fix the delay for 4/5
blue tower really needs upgrade, since the basic and cheapest is the best.. and a better grid layout for the enemies path, and a better layout for your towers.
flip the controls around, up for weapons... how you didn't find that annoying when you tested i don't know, erm, shotgun has a range of about, 1 millimeter, so perhaps increase that or put a small semi-circle as the mouse cursor, to show its' radius. besides that really good, integrate the kong api and get it some badges :)
well done, the basis of any game. now all you have to do is add... plot, characters, actions, fun... all that stuff, i made something similar to this in year 7. :>
spam some rockets and a plane and get a mountain of lag, waves still come realtime, even though towers and everyone's walk comes slowly, basically you get a billion slow moving creatures all on top of each other. also, the scores and cash randomly disapeers but then comes back.
how about, turrets must be dead before you are ,because you randomly just die like super instantly, with a whole screen of fighting happening, and you get to the stage where the game gets exciting, since there are some real targets... 4/5 till the instant death is fixed.