Great piece detailing Nintendo America's censorship rules that were used to tone down Japanese games for the US audience, removing skin, violence and fun.
This strict "no blood" policy came to an embarrassing climax following the SNES release of Mortal Kombat. Mortal Kombat had been one of the most violent games for the Sega Genesis, with wall-to-wall blood and guts. The graphic violence was one of its chief sources of appeal. When the game was released on the SNES however, in coordination with Nintendo's content guidelines all the blood had to be removed. Instead, when the characters smacked each other gray"sweat" flew out of their bodies, certainly a painfully awkward compromise. As well, the gory "fatality" moves, in which characters could formally execute their opponents by decapitating them or ripping out their heart were all removed. The game was a huge commercial failure for Nintendo compared to the success of the Genesis version, and the experience is credited with promoting a significant shift in Nintendo's attitudes towards video game violence.
(via Waxy)
Update: Tim sez, " "Friendships" are present in all major versions of Mortal Kombat II, including, most importantly the original arcade version. They were not (at all!) introduced by Nintendo in the SNES version to tone down the violence, as this fellow asserts."
