Добавил: The DSystem
Most of the time, this will appear as invisible in small places, like doors, but if it's massive like the example map shown in one of the images, which is Machine Attacks Episode 13:
This is a skin for those fed up of dead in the centre images taken from Google Images searchers, or terribly drawn no entry signs. Or if you're like me, I'm fed up of anything in my way when I spawn camp places. This is perfect. You will see a small "-" every now and then in some places, this is so you can identify the no entry sign, but depending on the map and how well you know it, you'll probably not need to know whether it's no entry or not.