Viewers were taken on a trip to the past on the latest episode of 'Running Man', when the show took a nostalgia trip by playing the infamous 'Xman' game.

'Xman' is one of South Korea's most legendary shows, airing in the early 2000's and achieving massive success both domestic and abroad.

For the tribute episode, the show invited heartthrob actress Moon Geun Young to play along. The rules were simple: one player would be designated as the 'Xman'. If the 'Xman' was not found out until the end, the game would be won by that person. Otherwise, the Running Men would be the winner.

With the games starting, the cast members started brooding on who could be the 'Xman'. Suspicion was especially placed on Lee Kwang Soo, who had lost pretty much every game he had been involved in, and Kim Jong Kook, who was gaining suspicion for the way he acted in front of Moon Geun Young.

Finally, it was revealed that Yoo Jae Suk had been the Xman all along, and his mission had been to get himself on the same team as Moon Geun Young, and stay there without being discovered. Having successfully managed to trick the entire cast, he proudly collected his shining badge.

Check out the full episode below!