This is how the room fading will look like:

There are rooms around this room, but they are drawn black (please ignore the grafics, these are simple placeholders). I had to insert something that shows you where doors are. Because as you can see, the door on the right corner is not visible for the player.
for shooting, mouse have to be over the enemy and not only pointing into his direction
What I mean with this is, that you shoot at what is directly under the crosshair and not only in the direction of the crosshair. So you have to move the crosshair over the enemy to hit him. Of course shooting will also work if you have the crosshair pointing on the ground. But then you will shoot on the ground

most players rather hold down a fire button
For preventing this, I think I will also add ducking and jumping. So you can cover behind boxes, tables,...
But of course also hold down the fire button makes fun, so I have the possibility to create some levels where you can take cover and others where you can't

Edit:
@Superku: Your game looks fun

When will we have the possibility to play a demo? ^^