Ok. I get it.
I liked the concept, but I think the technical needs to come to the party. I don't mean to put you down, but you need to up the realism on all counts:
More realistic recoil of the gun. More realistic flailing of the victims. More realistic screams.
For the audio side of things, I think copying and pasting the same screen over again is not going to cut it. Get some real honest screams (through acting, of course...) Get some more hard-hitting music. I like the simple piano licks but get some more of a score in there - think strings, tympanis with all the trimmings. Or go the rock band way. Make the music contribute.
Check out this spot - pay attention to the audio...
https://www.youtube.com/watch?v=XF4Zy1Exzk0
and...
https://www.youtube.com/watch?v=vL_tiB3lwI0&feature=related
But I'm not ruling out just solo piano as not workable. Check this one out:
https://www.youtube.com/watch?v=nPgMd_C83pw&NR=1
And one of my favorites:
https://www.youtube.com/watch?v=cw8JOQAJrjE
P.S. these were award-winning. 16 of them, too.