now my suggestions...
you already have lovely camera shake going on when you fly, but how about with the beat of the music? or probably in just very sudden pulses of volume or pitch
maybe some background stuff going on? I know this is probably pushing it for some peoples computer, so might want to make that optional, I think spectrum volume bars angled with edges would be epic, but it's your game
ratings are WAY too easy, you could increase people's level of interest in this game by making it harder and making them have to work for a good score
I think there are methods for detecting the tempo of a song, if you could set the speed of your car to the tempo of the song... a whole new level of awesome would surface
ok sensitivity could use to be able to go beyond 3.0 since speeds past 800 and such really require it and when you left click you should be able to speed up to 2 times your current speed this would also mean have fast your speed increases is doubled also while your mouse is held down, this is just to make the beginning less boring and other easy parts
double jump is a bit overkill, maybe you should be able to upgrade the second jump, because before I bought it I was able to barely get 250 meter, but once I bought it, the next game I got over 800 meters
I've only played for about 30 seconds and I can already tell I love this game, it's a bit laggy due to how much is going on, but the game amazing amount of content and work put into it make up for it, now back to this...
it would have been a real nice thing if jumping while falling was more successful, good, but bad job with the movement system, too loose, my guy flys all over the place and half the time falls to his death
place only multi fire turrets in corners and places where they can hit a lot of enemies, doing this will kill off just about any horde, so you can beat expert on a lot of missions
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Next version makes the max sensitivity higher :)