The term Gun Porn did not originate with the videogame Black. Gun Porn as a term meaning photos of guns that display them in the same carefully posed and lighted manner as the models in traditional pornography, has been around for a long time in firearms and shooting cultures.
The creators of the game Black were using the term with this meaning as an example of how the guns were the stars of their new game.
"did you check out the new issue of Guns & Ammo? It's got some great gun porn.