This was a pretty fun game, though I'm glad you put the limit around 30k because around that point it was getting hard to focus.. you never get a break. :P Would be fun with a more level-style build-up, where you buy upgrades between levels and it gets progressively harder without all at once. The enemy variation is nice, though they all look pretty much the same (how about different colors/armor/etc?), and the power-ups were a much appreciated addition. One thing that bugs me a bit is the background though, feels like you could've put some more work into that part, otherwise it's nice and simple. Keep it going!
-cd-