Awesome game. I loved the first and this one is even better. A couple bugs, though. I was playing Endless City mode and about 4 minutes in after I got hit by a couple planes and a bunch of my birds died, all of the audio stopped playing except for the background music, and one of the bird calls (goose, maybe?). Then, a few minutes later when I lost, at first it looked like everything was working fine (the "lose screen" popped up), but when I clicked on the button to return to the menu, the screen returned to the gameplay, showing the state of the game when I lost. The animations of the planes and the stray birds were still playing, but the game wasn't scrolling, and there was nothing I could do to un-freeze it and return to the menu.
One suggestion. I always move my mouse off of the stage by accident when I am trying to dodge bullets. Anda as a result my plane always flies up to the upper left hand corner by default, crashing through several enemies and sometimes even killing me. Perhaps you could make the plane defult to the bottom of the screen, not the top, which I think would reduce the amount you are hurt each time the stage loses focus of the mouse. Even better would be for the plane to remain right next to the edge of the screen where the mouse last was.
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