For a simple little Arcade-style game this was pretty fun. It's actually kind of addictive in a way. I had more fun playing it that I thought I would to be honest. It just goes to show you that, on occasion, even the simplest of games can sometimes be better than those loaded to the hilt with extra content. "Less is more" as they say.
While I actually liked the music (It kind of reminded me of World Six's World-Map music from Super Mario Bros. 3), it did slightly get annoying after a while. Though I admit that it suited well with the theme of constant oncoming danger that was happening during the game. Another issue I had was the Advertisement at the top. While it didn't actually hinder your view or anything, it was still kind of distracting. Also it would've been better if you didn't have to sign-up to anything in order to have your name/username submitted along with your score. Would've preferred to just enter my username from NewGrounds (Like with Santa Run 1&2 and the Infectonator series) and that be the end of it; Score submitted.
Other than that though, I really had no problems with this simple little game. Really had fun playing it and wouldn't mind a sequel of sorts to it. (Though the sequel probably WOULD have to have atleast a FEW additional features to make it a little more interesting.) Still a good game though. Good job on this and wouldn't mind seeing more games from you in the future. :)
P.S. I remember when this game was in NewGrounds' "Under Judgement" category. Glad to see that it made it through the Portal. :)