Blue Mountain Lab. is a subsidiary scientific corporation of Black Mesa. It studies AUs - parts of the real world artificially changed by the infosphere.
The infosphere assumes that the entire material world consists of elementary particle that have certain properties in the world, which are prescribed by a kind of "program code" of this particle. This "program code" can be changed, thereby changing the particle and its properties. Thus, man is now able to change the material world, however, due to the underdevelopment of science, as a result of such changes in the "program code" a huge number of anomalies can appear.
When the "program code" of a certain part of the material world is changed, this part of the world disappears from the real world forever, leaving an empty field in its original place, on which small anomalies sometimes form.
The already partially changed part of the real world also acquires a huge number of anomalies within itself and moves to a large and unknown to science space called structural void.

The main differences between the AU and the real world are:

• Empty and illogical spaces
  
• Changes in the atmosphere, lithosphere and hydrosphere
  
• The disappearance of artificial structures and things, often small ones (doors, electrical appliances, small items)
  
• Simplification of large structures, their illogical construction
  
• Rearrangement of buildings and objects, their illogical arrangement in the AU (unlike reality)
  
• An increase in the brightness of light or, conversely, a degradation of light until it disappears completely
  
• Partial absorption of reflections
  
• Partial or complete change in the properties of materials or objects
  
• False windows (their presence on one side and complete absence on the other)
  
• Presence of mini-anomalies (radiation, information (changes in text, data), temperature, sound)

AUs aren't infinite, they have their own boundaries, which, if crossed, can lead you out of the AU into the real world.
Creatures in AU are extremely rare, in the form of one or several individuals. Creatures often stay in one place, familiar to them, and are extremely aggressive.
There is no connection with the outside world inside the AU, it's absolutely impossible for a person from the real world to contact a person who is inside the AU. There are some AU exceptions that make it possible to contact the real world, but such AUs are extremely rare.
Basic navigation tools in the world, such as a compass, won't work in the AU at all, due to the unstable electromagnetic field. For the same reason, any technology that relies on the use of an electric or magnetic field can deteriorate and become inoperative inside the AU.
This is why all Intelligence Research Groups (IRG) are advised to use devices that operate on different physical principles.

The name AU is wrong in relation to those worlds, since they aren't a reality where everything went a different way.
But this name was the first and was fixed in the terminology, so it became the main name for these strange worlds.

The collection currently consists of (quantity):
AU: 6
Blue Mountain Laboratory: 2
AU simulation (APB): 2
Post-portal crisis: 2
Other maps (have partial connection with BM Lab.): 1

And now you see that it didn't last long? Now you see the consequences of it all.
When the Resonance Cascade occurred, a wave of chaos shook the Earth, destroying everything in its path. Cities were destroyed, countries were destroyed, the Earth was destroyed. This wave also destroyed Blue Mountain laboratories, and what did it lead to? Pandora's box has opened, all these dangerous developments that created entire worlds have now come out into the real world.
Suddenly, another storm swept across the Earth - portal crisis. It will pass by, and anomalies will appear on the tortured earth: fire will change color, water will become dry, and the Sun will cool. Where there are no anomalies, it means that this land will not exist - entire continents disappeared.
And yet, if anyone remains, he will be destined for a worse fate. There are small anomalies, but there are large anomalies, and this means that now, where it used to snow twice a week, it will snow forever. And where there was no snow, but just a desert, there is now dead, dried-up land. And these large anomalies will spread across entire worlds, from mountains to seas.
Thought that was it? But no, those small lands that were near the Blue Mountain laboratories now had new diseases: new buildings grew on the body of the old world, new clouds appeared and new distortions of the terrain. The Blue Mountain laboratories that contained certain strange worlds have now allowed them to enter the real world and spread their influence there. From now on, strange worlds were not somewhere in the middle of a structural void, but were also on the body of the old world.
The old world? And it's gone now, such chaos is not under anyone's control, and as I told you, entire countries were destroyed, and anarchy came in their place. The old world order has fallen, a new world order has arrived, but for how long? And all this until creatures that are different to us, the gods of the universe, intervene in this damned world.
However, are these gods of the universe important to that lost soul in this damned world, if now its only question is: Will I survive today?