i think it was programed very well, but it seems a little "Sloppy Joe" Fix it up a little, try to make the enemys go around each other instead of just running them over. Shadow the sprites, make the controls easier. And as Mikea15 said, let the 'turrets' be selected when the mouse has a collision with the box.

still it was way worth playing!

The game is alright, nothing special to look at, but it is solid nonetheless.

Only 2 major complaints.
1) It was too easy. on the hardest difficulty I had all my towers set up, and released evey single enemy left. Sure my computer ran slow for a bit, but only one enemy escaped. The towers are either too powerful, or the enemies not enough health.

2)As mike said, the controls felt kinda clunky for a tower defense game to me. clicking on a cannon sometimes did absolutely nothing, and once or twice it auto upgraded them.

all in all, I give ya a two out of five. Has the makings to be good, but those two flaws are kinda large.

Overall the game is good, but you should make the controls more fluid. For instance, when you want to select a cannon, why can you only select it when the mouse is exactly over the cannon and not over the square holding the cannon?? It would be much easier. Also, the sound doesn't fit the game...