i must say this is highly enjoyable, the upgrades are a bit confusing *as they do not tell you how much they will increase the damage/rate of fire but overall i enjoyed playing this.
beat the last boss on frantic *i assume thats harder than hard, with the last ship and 4 homing missles. i like the homing function i feel its a bit over powered but nothing wrong with that. it would destroy EVERYTHING even when i did not move, i loved it. last boss was a bit bland though...just stuck to the left side and finished him rather quickly.
make a sequel with even more upgrades/power/enemies/levels/customization and you have the potential to make the next "great game" try looking at enigmata and genus revenge. you can probably compete with that if you keep making these kinds of games!