Mortal Kombat could end up in a crossover game with other fighting franchises, but such a move would be difficult, series creator Ed Boon has told G4TV.

With Capcom's Street Fighter teaming up with Namco Bandai's Tekken, Boon was asked about his thoughts on a similar match-up for Mortal Kombat.

"We absolutely have thought about it," said Boon. "One of the obstacles is that we're an M-rated game and all of the other ones, for the most part, are T-rated games. So it's the same challenge we had with pairing up with the DC characters."

He added: "But we've all dreamt with crossing over with Street Fighter or Tekken. Killer Instinct was also one that was coming up since they were an M-rated game as well. But I'll tell you that we've had many, many conversations along those lines."

Mortal Kombat is the highest-selling fighting game of 2011, with over three million copies sold worldwide.