Complete and utter rip off.
I'd really like this submission if any of the concept was your own. I mean for crying out loud it's a complete copy of "Desktop Defence" with different, and not neccessarily better, graphics. You cannot have missed it- the level up system is identical, the prices are identical, and for crying out loud the highest gun levels are identical! You even kept the tower size as twice the size of the enemy!
The only differences I can see between the games are the graphics, which must be where 90% of your work went, and removal of some key features from the original- the 'cute' graphics style, the hotkeys, the massive field scale, the level-warning bar (that tells you several levels ahead what's coming next) and any shred of originality.
Don't claim someone else's work is your own. It's not good. Sure, you made it slightly prettier, but it's still their concept, their design, their balanced game engine and their sweat that went into it. If only there was some way to Rate on the basis of originality... I suppose 'style' will have to do.
Anyone who liked this game, google "Desktop Tower Defence". You'll see what I mean.