A fantastic haunting theme that builds up to an eerie finish. It starts off slow, and you can hear the tension rise as it goes along. I really would like to know if this was maybe just Zimmer or Howard's idea (because it sounds like something Howard would do) or if it was a combination of both.
Here's something you can try with this song (to show it's tension):
1.) Play Ridley Scott's "Alien" (any version '79 or '03)
2.) Go to 1:10:36 into the film (you 37-38 seconds, if you like). If you haven't a timer, go to where Dallas says "Okay, Ripley." after she tells him the vent is open.
3.) Start playing "Watch the World Burn." at that time.
If it works, the song should end just as Dallas runs into the Alien. Fits perfectly (to me anyway). :)