The two multiplayer levels are called Reactor and Biosphere. In this zip file you will find two new Aliens versus Predator Gold Edition multiplayer maps. Precipitous paths forming an endless loop constitute the only barrier between the player and certain death.
Level is fairly freeform, i.e. a largish outdoor area split into different areas by walls pillars.
Hazardous natural environment is natural to this level. Influenced by Quake III Arena in the way it manages to create a claustrophobic environment from what appears to be an open space. After extracting the levels into the directory there will be two versions of each level in the multiplayer game configuration menu.