It was well known even before the filming started, that the main writer was a complete arse with no clue about anything. I'm just sorry that you actually had to pay to find that out.
Belive it or not, that version you saw actually was a million times closer to the game than the script was when filming began. Originally it was set on a distant planetary out-post (some made up planet name I can't remember) and was based upon a virus outbreak ala Resident Evil.
