I technically already did this one other on my other requests story, but I'll go more into detail here. Have Okabe Rintaro/Houinn Kyouma, as well as all the Future Gadget Laboratory members. Have the characters from Steins; Gate Zero, and Mr Braun and his daughter. Have it so that the Steins; Gate Zero people have not ever met Okabe or any of the others just yet, and that the other characters all come from either when they're just starting to do the Phonewave experiments or have it be pre- Load Region of Deja Vu.