Gave A Lower Rating Cause of how rushed this game seems.. I Mean i know its your first Html5 Game but i believe this should have had a little more work done to it before releasing.. Make your next goal as adding movement/walking animations... After that add health to your player instead of just instant collision death..

Well it needs some improvement it's not bad for your first game tho , what you need to add :
1.Music and sound effects
2.A legit story with levels
3.A health bar cause it's annoying to die only being hit 1 time
4.more guns and firing animation and also ammo limitation and reloading effect
5.Different zombie types like runners , bombers ,ect....
So ya hope you will add those im sure it will be pretty awesome if you do so !

I am happy for your achievement of making your first HTML5 game! But the least you could have done is make the game more interesting, add some sound effects, a hud, some achievements or missions.
But no, you decided to put a game anyone can make in less than an hour. Please, don't do this again.

.5 star for it being your first game though.