This game seems to have some kind of rendering problem in Chrome. I get maybe 5 fps under Chrome whereas it's perfectly smooth with Firefox. (No, it's not my computer, I can run any modern game with good framerates.)
Pause doesn't work. If I pause with enemies on screen I hear damage and have reduced health when I unpause. Did you make the pause button stop enemy spawning but not actually freeze the game?
 "Strike Force Heroes"){kind=icon}
 "Pixel 2"){kind=tracking}