Cool concept! I like the idea a lot.
It would be great if you could get more than one guard with a shot from the bazooka. Right now if two guards are next to each other only one of them gets hit. I can see why guards can walk through the fires given the time constraint, but maybe there could be a timer that allows the fires to hurt guards for the first second or half second that they exist, so you can kill more than one guard at a time.
Also, the hitbox for the player is really big, so sometimes there wasn't a clear collision between a guard and the player and the game would end.