Ohw very nice game !!!! I like the theme and play method :D
I played two levels.
I found that the window was a bit small, cant your run this in a 800x600 or even 1024x768 ?
Great music tunes, though I though the volume of the machine gun was rather loud compared to the rest of the audio.
Also, the effectiveness of the machine gun nearly rules out the need for them missles.
I bought missles after level 1, great that a shop is available before hand, but I couldnt buy anything when i started :( theres a shop, gimme some cash to buy anything ... something .. pls lol
when using the mouse, clicking once fires two missles
Perhaps make click right switch weapons for mouse users ? seeing as the plane follows the movement of the mouse :)
At some point near end of level two, I was pondering when enemies would come, perhaps some indicator of enemies left.
Great work :D