The sound effects very quickly become annoying, even painful; maybe try choosing somewhat softer sounds.

Good job, especially for six hours. I caught one error:

> ai.lua:13: attempt to index field 'target' (a nil value)

I'd played the game once and restarted, played for a few seconds, and then the error ocurred.

I got the same error when I died. I also couldn't get the wasd keys to work, but it worked fine on my 360 controller. I thought it controlled pretty well and I liked the upgrade system and level design.

Nice game, but I think that there is a problem with the shoot, sometimes I an shoot 3 bullet in a short period other times only one.

Enjoyed it a lot.
At first I thought it would be a bit boring and too simplistic, but the power ups and neat little explosions and nice SFX actually brought together a nice shooter. :D
Wish there were more levels! :D

Nice game, but the game always end with a crash or an error.
The option system is good I like the fact you have to read then grab the falling option. I think it really improve the replayability of your game.
On level 3 I think pierce is way better than bounce ( even if you have spread ). The autofire should also increase your firerate, because you can emulate this powerup by just bashing your 'J' key.

WASD also did not work for me. (And also got the same error on death). Not too shabby for 6 hours though :)