This is a flash revolution!
You have brought the world of doom into flash, I need to get a hold of that actionscript (if you could email it to me)
You got a five because they were lacking, easy improvements would be to add some detail and lighting into the walls, maybe some blood stains or posters on the wall and also some lockers would have helped.
This is a newage style that is quite exceptional, the only thing that i can think that would make it a bit better would to boost up sound and graphics.
Or lack there of, add some background music and maybe even shouts and death cries and your score would be a ten.
Easy ten, a little blood here and there and of course an overall violent theme (thats what pico is all about!) You could improve the look of the blood and maybe make some dynamic blood stains on the gun, but these are all minor.
Another easy ten, with an engine like this a ten is the minimum i would give (and unfortunately the maximum also)
There really wasn;t any humor and that was expected. It didnt harm your overall score at all
Amazing work and I really need to get my hands on that code.