OMG! Obviously inspired by Nintendo's efforts to branch out their big-name characters to 3rd party franchises, the developers of Unreal Championship hav decided to include Raiden in their latest endeavor: The Liandri Conflict.
Source: http://xbox.ign.com/articles/585/585984p1.html
"It was pretty seamless since both teams thought it was a really fun and cool thing to do," Allison continued. "We were near the end of development on MK when this idea took off so the biggest challenge was getting the content Epic needed to put Raiden in over to them on time. It was pretty drama-free, actually; the basis for the art files was easily transferred into the Unreal engine. And Raiden's got some new and some old in UC2. He packs a pair of double Enforcer pistols and an Energy Staff just for the Liandri Corporation's UC2 events, and he has a few special moves based on his charged lightning attacks in the MK games as well."
Source: http://xbox.ign.com/articles/585/585984p1.html