As I said before, I was strongly influenced by those dark and baroque illustrations on original Rogue Trader book with those massive and scary marines, done by John Blanche, Tony Ackland, Tony Houg or Will Rees.
First Edition of WH 40.000 was a real explosion of art and creativity, cause they were starting to define all that universe and the game rules. With that book you can play the game just as a wargame or even a roleplaying game.