LV 426 is a planet (known as Acheron) where colonists have their facility.
Hadley´s Hope colony,which has it´s own Atmosphere Processor.
I have not seen it before in the movie.
Something similar was in the Toltal Recall,but
Aliens was first....

There are many things to build.
Moduls, Comunication tower, landing grip, atmosphere processor,
powerloaders and other vehicles...even a Jorden Tractor.

So .I´ve decided to split this project into two groups.
The 1´st group is AIRCRAFTS & VEHICLES...there will be
all that cranes,bus like vehicles, prospectors (Jorden tractor),
even small dropships ( 01 & 02 ) with small APC Carrier.
The 2´nd group is PLATFORMS & BUILDINGS ...there will be
the whole Hadley´s Hope colony (all that habitat modules), garage,
landing grip even the comunication tower and......
at last the huge Atmosphere processor.