Panzer Dragoon R-zone was a Tiger R-Zone game for the short-lived system. It was one of the few launch titles licensed by Sega, being released just a few months after the original Panzer Dragoon. It was the first game in the series that was not developed by Team Andromeda.
There is no plot, simply a nameless character on an armored dragon attempting to keep a dark dragon from reaching a tower while shooting and dodging robots.
Source: Wikipedia, "Panzer Dragoon (series)", available under the CC-BY-SA License.