Excellent Game
Listen, I play alot of defense flash games out there but this is by far one of the best. It's mostly orginial for defense games and it's highly addicting - two of the most important qualities in a defense game. There's so many options, ways to build up your defenses, etc. that it makes the replay value very high. Overall, it's a great game.
Scoring:
Postives
+3 Orginiality
+2 Replay Value
+2 Graphics
+2 Features (Upgrading, specifically)
Couldn't really find any negatives, although I don't feel this submission is revolutionary enough to receive a ten.
Overall: 9 / 10
Improvements: Can't really find anything that needs improvement.
Suggestions:
1) Make it so that you can actually use functions for bonuses. (Music player plays music, internet explorer opens up a "web page" with tips on it or something.) It would make the game seem like your actually defending your own computer.
That's just about it. Good job. It's an impressive submission.