"RBR" is an acronym that stands for "Ruled By Robotnik". It used to define the era in Sonic the Comic continuity when Dr. Ivo Robotnik ruled over the planet Mobius as its tyrannical dictator.
Dr. Robotnik managed to conquer Mobius by taking control of the Omni-Viewer, a sentient machine entity that resides in the Special Zone and is capable of moving through time and space. How Robotnik managed to enslave the Omni-Viewer has never been specified, but with it he was able to lure Sonic the Hedgehog into a trap and send him and his friends into the future. His orders were not very specific and so the Omni-Viewer only sent Sonic forward six months, but in that time Mobius was without a hero and so no one was able to resist when Robotnik's Badnik armies spread across the planet, conquering whole zones and enslaving their populations. By the time Sonic returned from his time displacement, Robotnik had already established his global empire.
Reign of RobotnikEdit
Robotnik ruled over Mobius with an iron fist, turning whole zones into labour camps and abducting countless innocents to be converted into Badniks. Also during his reign, the doctor constructed multitudes of factories and other facilities across the planet that would produce high levels of pollution, contaminating the environment and atmosphere. When Sonic established his group of Freedom Fighters, Robotnik came to realise that Mobius now had a symbol of hope and made a point to repeatedly victimize certain zones in order to crush that hope.
The seat of Robotnik's power was located in the Metropolis Zone, which would essentially serve as Mobius' capital during and after the doctor's rule. From his Citadel, Robotnik would devise all manner of plans to destroy Sonic and the Freedom Fighters as well as commune with his various planetwide agents and facilities.
The era of RBR came to an end following the appearance of the Black Asteroid in the skies above Mobius. The Black Asteroid was once an ore mine in the Special Zone that had been turned into a prison for the ultra-powerful Super Sonic, Sonic's former alter ego turned separate entity. In order to save the people of the Special Zone, Sonic - who was trapped there at the time - convinced the Omni-Viewer to teleport the Black Asteroid to Mobius. Within the asteroid, Super Sonic was charging up a massive amount of Chaos energy to destroy his prison from within. This burst of energy would create an electromagnetic pulse that would disable all electronic machinery within the blast radius. When the Black Asteroid exploded, the EMP blanketed all of Mobius, disabling all of Robotnik's technology and destroying his empire in one fell swoop. With Citadel Robotnik destroyed and every Badnik across the planet wiped out, the people of Mobius were finally free. However, Robotnik escaped justice and went into hiding so that he could plan his revenge against Sonic and all of Mobius.