Fun little game, took a few attempts to get through but enjoyed it! The health/ammo management was interesting to balance. The first few times I didn't realise properly why I couldn't fire so often - although I think that's on me for not properly reading through the mechanics.
I confused the heat bar at the top for the health/ammo earlier on - perhaps this can be better indicated by some other icon next to the bar. I couldn't find good uses for the grenades so much as by the time they exploded, the antivirus had moved past on the times I tried them.
As a side note: sound was working fine for me in a Firefox based browser on Linux - just thought I'd let you know as you mentioned it in your description.