Okay this is a bit odd, but while giving it another try today, I was able to play the game. However, it worked only once. All other tries returned an error "couldn't render text to surface". Even a complete system restart would not let me play again.
edit: it occurred to me that the only thing changed was the score. When I removed score.dat, the game worked again.
edit2: okay even more weird. It seems something is corrupting your score.dat file, because I now was able to play the game again with the score file.

Some observations.

Resolution:
I don't have a particularly high resolution (1280x1024), but I find running a game at 640x480 is no longer of this time. Use 800x600 at the very least, but even that is becoming old with todays hardware. You would be doing yourself a favor too, as it gives you more room to play with.

Speed:
It's running too fast. The first three lives I played though, I had no clue what was happening and I died within seconds, because everything was rushing by so fast. Mind you, it's not too fast to play, it's more like a movie running at twice the speed. It's enough to follow what's going on, but too fast to react on events.

Movements:
The physics are odd. For instance when you get shot, you speed-dive towards the ground with at the very end a sudden angle change. (I assume that is due to preventing the plane leaving the screen so the horizontal movement is ignored leaving only the vertical). I would suggest adding some simple physics to your plane and debree.

Unclear goals.
It's unclear to me what I have to do. Obviously I need to at least hit those that shoot at me, but why is it that I can sometimes destroy buildings with a single hit and others stay in tact? (It's impossible to hit them twice).
Edit: I realize now that I need to hit something dead-on. There is no 'splash' damage so to speak.

Bugs.
There are still quite a few bugs. Some I noticed are:
- I seem to get hit by bullets that are a miss. (no pixel perfect collision detection?)
- When I die I sometimes don't respawn.
- There are explosions and bullets after a respawn on the left side of the screen. As if my previous plane is somehow getting destroyed again.
- When using escape, lives are set to -1. all enemies disappear (sometimes), I then see my plane get destroyed and then I go to the menu (sometimes only after using spacebar). All in all a strange way to end the game.
- sometimes when reaching 0 lives nothing happens afterwards. I have to close the game to continue.
- I can still drop bombs when I'm destroyed.
- some strange stuff with the score file as mentioned earlier.

For a 0.9 version it's certainly not bad. You have the basics covered, now it's time to smooth out the rough edges.