Seems good, but...
The art style is good, the particle effects are great, and the idea is pretty decent, but I came across a rather unique bug. I start the game, enter the first wave, and instantly have problems.
It seems the collision detection is fucked up, because the bullets pass right through obstacles and the players, so as of now, my Hank has been stanging in the same spot with a guy firing at him continuously, and he hasn't suffered a single bit of damage. Nor can I damage the guy. The only way I can damage them is by laying down a trap or mine, which work perfectly well, and those are some great gibbing effects.
Bullets will hit invisible objects and give of sparks, and if I play for long enough and fire randomly, very occasionally, I will hit something invisible that gives of a blood spurt.
I have reloaded the page several times, played in a popup, even downloaded and tried to play it, and all to no avail. Whatever this bug is, (looks to be something wrong with collision detection), it's a game-killer.
I'll give you a 5/10 because the graphics are good and the gameplay sounds solid enough, but fix the bug and maybe put some more variable terrain in there and it'll be much better.
Kudos for making the game and getting 2nd, btw.