No real challenge. The main sprite is taken directly from the metal slug series. The enemies don't really do anything. Music is extremely underpowering. very little in the way of sound. Not a bad first effort. But it needs alot more. And be creative. Don't just take the sprites from an existing game.
I encountered some glitches.
1) If you jump up and make contact with the side of a wall, you cling on to it.
2) I experienced one glitch where I was supposed to fall off the map, but I just floated around on the bottom.
The enemies look a little bit like snoopy.
After the big one is killed nothing happens.
The music can't be tuned off.
There is not a hint of a challenge in shooting enemies who do not try to attack or dodge.
If you make it a full game ill be happy to play it. Even if you only came up with this you should have pay attention to things like an ending more sound effects, maybe each stage different theme and what's with the shooting only in one direction, its ok if you are making a "scroll" type game and you are focusing on what's coming ahead. I only commented because I like the character. Oh and does the action take place on a giant moving platform? When you stay still background keeps moving...
The main player is a default sprite, so that definitely loses points. But if you were to make this game entirely original and add more enemies, levels, and even a few powerups. You might get somewhere. As of right now though it's a horrible game that requires no strategy.