The Chrono series is a legend in the rpg world. It started with Chrono Trigger for the SNES, got its story continued with Radical Dreamers, a niche game for Nintendo's SatellaView service and was finished with Chrono Cross on the PlayStation. The games were widely praised by gamers and press alike, but never saw too big of a commercial success.
This is why the proposed successor, "Chrono Break", never saw a release.