Green and blue, these are the colors of the code discs.
Well, one of them serves to access the interior of the UFO, but the other is also necessary to continue the level, because it gives us access to the room where the UFO and the dead aliens are, or whatever they are …
To get the other disk, something had to be done at the military base that allowed access to the area where the object is. Of course, what could happen at a site like Area 51? Anything, really!
You have to remember those moments on the Nevada level to find the solution. And do not look any guide!
What did you have to do to reach the second code disk?