There is no doubt that the graphics and sound are top notch, and the HP regen fits really well with the style of the game. However, there are some glaring faults that mar the experience.
1) It still won't work on Firefox for me. I have to open up ole Safari.
2) Gameplay is way too repetitive. The first board pretty much sums up the whole experience.
3) Jumping is overemphasized. I feel like a female Night Elf on WoW.
Perhaps you can make the game more dynamic with a few adjustments. For example, allow players to gain weapon proficiencies after a certain amount of usage, increasing the accuracy of shots with that gun. Or, since the game is crazy gory anyways, let people use bodies as temporary shields, allowing them a brief respite from the aforementioned jumping marathon. Perhaps a 'berserker' mode. Stay in the red for a long time and you become invincible and more powerful for a short time. Just some thoughts...
The graphics and sound effects are nice, but there isn't really any strategy to employ. Thus the marathon boards were painful. Only kept playing because of the badge...
 "Thing-Thing 4"){kind=icon}
 "- Rose -"){kind=icon}
 "Knights of Rock"){kind=icon}
 "Kongregate Chat"){kind=icon}
 "Hover Bot Arena"){kind=icon}