The mythos is all the H R Giger designs & concepts which inspired the sets & the mystery of the massive spaceship wreck which they set down to explore. It was this that Prometheus set out to 'explain' but IMHO singulary failed to match it in terms of awe, by becoming bogged down in inane plotting & missing the central issue. That the iconic space-jockey itself turned out to be a space-suited humanoid was a cop-out too far for me (especially as Giger's original jockey was shown wearing a transparent helmet) much less their motives & modus operandi.

Still looking forward to the DVD special edition though!