Trent reznor was hired as a sound fx guy dufus. You should know that. He isnt the tech guy responsible for implementing true 5.1 dolby digital technology.
He was the one doing the sound design, including that which uses true 5.1 sound, "dufus". True 5.1 sound is where the sound is designed to specifically take advantage of a 5.1 speaker setup, not just spread the default sounds out on 5 speakers and a bass.
The ragdoll physics in Doom are incredible. As are the Half Life physics
The ragdoll physics in both games look like crap. Ragdolling in all games right now looks like crap. No existing ragdoll system has yet to consider a muscle system in addition to a bone system. A human body does not turn into lighter-than-air silly putty when it dies.