You step through the door, noting the three holes in it, and also wishing you had brought more bullets. It's almost completely black, with only a few beams of light coming from the rotting door behind you. You look left and right, seeing nothing. You ears tell you differently. You hear heavy breathing straight ahead. You don't like this.
You pull up your gun and aim towards the sound you hear. Your pretty sure your pointing in at least the general direction of the source of the noise. However, you've just seen how bullets don't work. You wonder if you made the right decision about shooting thro the door. A little late for that now. Here is something that needs your attention now.
So, do you shoot first and ask questions later, or do you try to make contact with the creature you can't see.
Do you want to shoot, or do you want to talk.