If you thought the war over the brutal video game Mortal Kombat reached a peak last week, think again. Mortal Kombat II, a new and possibly bloodier version, will hit arcades before Christmas-with a home edition sure to follow. ”When you have a success this big, you build on it,” says a spokesman for the game’s manufacturer, Midway, which plans to install 25,000 Kombat II units in convenience stores and video parlors worldwide. The announcement comes on the heels of meteoric sales of rival Sega and Nintendo home versions of Kombat I ($65 million internationally in the first two weeks). With vivid depictions of decapitation and impalement, the bloodier Sega versions have prompted debate on kids’ entertainment. ”Games are more dangerous than violent cartoons,” says Dr. Carole Lieberman of the National Coalition on TV Violence, ”because they actually involve kids in the killing.” Counters Allyne Mills, a spokeswoman for Acclaim, the company that designed the home versions, ”This game is fantasy. Kids know the difference.” To mollify parents, Sega is rating its games. But the MA-13 (Mature Audiences: Parental Discretion Advised) it gave Kombat has drawn the ire of the Motion Picture Association of America. ”(Sega) came to us and asked to use our ratings. But we said no,” says MPAA’s Elizabeth Barnes. ”Now they’ve developed their own system, and it’s potentially confusing to parents.” There’s no litigation in the works-”just an exchange of letters,” says Barnes. But if Sega doesn’t alter its ratings-or tone down its games-there could be another bloody battle ahead.