Thanks for playing my game and for the feedback :)
I did consider allowing the player to stun the monster with the gun but, in play testing, I found it made the game a bit too easy so I changed it so the monster takes a step back instead.
Firing the gun also creates a loud noise that will be highlighted on your map, giving the player a way to pinpoint their current location in case they get lost, but I'll admit I didn't really communicate this to the player.