Sylvester Stallone is planning a fifth Rambo film following the success of his ultra-violent 2008 sequel. The action man has revealed he's started writing a fifth instalment of the franchise - but the next Rambo movie will be very different from the shoot 'em up jungle adventures his character is most famous for. Stallone tells Swedish newspaper Metro, "I would like to take Rambo to another genre, experiment a little with the character. It would definitely not be another war movie. "I can't go any further with that than what I've already done. What it's going to be like, I'm not going to reveal at this point. But I'm already halfway though writing the manuscript." Stallone's Rambo films started more than 25 years ago with First Blood. Rambo: First Blood Part II and Rambo III were released in 1985 and 1988 respectively.