I HAVE KILLED ALL THE ALIENS NOW IT SAYS ASSIST DELTA TO THE EXTRACTION POINT AND I HAVE BEEN ALL OVER THE PLACE MANY TIMES AND CANT SEEM TO FIGURE OUT WHERE IM SUPPOSED TO GO,AM I SUPPOSED TO C-4 SOMETHING TO MAKE ACCESS TO A NEW AREA ??? ANY HELP WILL BE REALLY APPRECIATED,THANKS!!

Use the nano vision to locate the objective? Err, not nano vision but the binocular like vision thingy, forgot what it's called. Normally the areas are pretty linear so just look at where you came from and go the opposite direction..

Also, caps lock is cruise control for cool.

If it's the one I'm thinking of, you just walk to the end and there's a small foor with an ammo cache inside.. then you just walk out the other end of the room and it's done.

use Tactical Visor for your objective. Press B