Two anecdotes. Perfect Dark, the N64 game released around the year 2000, got given an 18 certificate in the UK because of the fact that blood can splatter from shot enemies onto walls. Raiders Of The Lost Ark, the film released in 1981, nearly got refused a PG [edit: thanks, bena] certificate because it showed exploding heads. The picture you linked depicts both of these acts of violence, whereas Wolfenstein 3D does…
You probably mean PG, as that's what Raiders was rated.
PG 13 was created when Temple of Doom came out, because the gap between PG and R was too great. http://en.wikipedia.org/wiki/Motion_Picture_Association_of_A...