This gives a mix of a style between Final Fight, Super Contra and Mega Man. Regardless of whether that was what you were going for, I like that feel very much. I love the level design, and the regular enemies are fairly easy to avoid, except for that one gun which blocks your way and seems to have homing bullets (this really feels like bullet hell...). Admittedly I like the regular enemies -- they look like they've been fitted for a Kirby game of some sort *coughcoughKirby'sAdventurecough*
The bosses can sometimes be hard (I have a feeling one of the bosses actually has HOMING bullets, rather than normal bouncy ones). I don't know how, but I managed to finish the demo. The control scheme is great, as is the music and the general ambience.
For a work done in a single day, this is impressive!
For the finished work, I would suggest:
1) a story and level progression a la Final Fight. This would mean different ambiences, different pieces of background music, and a motivation for all the shooting and killing. Who is our antagonist?
2) Checkpoints. Because right now a Game Over means instant restart from the beginning, which can be kinda frustrating at times, especially when we've gone quite far into the game.
3) Varied enemies?
I await the final version of this work -- there is a lot to be anticipated! :D