Radical Dreamers was released on the Dreamcast system. From what I understand it’s just the Manor House section of Chrono Cross using Kid, Guile, and Serge. When the Dreamcast flopped, it was expanded into CC.
The impression I got from reading about Radical Dreamers is that Chrono Cross would cover everything in the story that this game did, so I wouldn’t have to play both.
I’m gonna get started on CC again after I have some lunch.