Nice use of Metal Slug sprites.
Reasons I voted accordingly-
Graphics: The backgrounds and sprites are from a game and can be found all over the net. I'd usually give a 5 for that, but you got an extra point because of how fluid the actions were. You obviously knew what you were doing here.
Style: +1 for the use of the RE health bar. I love metal slug, but this type of game was done before. Not quite as good as this, but done before. You would have got a 5 if it wasn't for the Resident Evil/Metal Slug crossover.
Sound: These also sound exactly like the Metal Slug sound effects. However, they're more clear than most other rips I've heard.
Violence: Self explanitory.
Interactivity: It's a game, which means it's automatically interactive.. But still, you can upgrade literally everything. bad-ass.
Humor: Low because zombies are a very serious matter.. The fate of the world is at stake here, man! That's not funny to me!
Overall: 8. I loved it in general.
I think you should make Metal Slug based zombie movies, personally. Maybe even choose your own adventures. That would be great, man. Keep it up.