The Roboticizer is a machine from the Sonic the Hedgehog franchise, seen primarily in the animated shows Sonic the Hedgehog (SatAM) and Sonic Underground, as well as in the Archie Comics series. As the name suggests, the Roboticizer is capable of converting living creatures into robots. Throughout the franchise, Dr. Eggman/Robotnik has used roboticization to turn innocent animals into his robotic slaves.
Pre-Super Genesis Wave
In the Pre-Super Genesis Wave continuity, the Roboticizer was a major medical breakthrough. Invented by the Kingdom of Acorn's Minister of Science Sir Charles Hedgehog, the Roboticizer was intended to be used to treat the sick and injured by converting damaged body parts into mechanical devices, repairing broken bodies and curing diseases. However, the Kingdom's warlord Julian Kintobor (whom Mobius would come to know as Ivo Robotnik following the Great War) stole the plans for the Roboticizer and sabotaged the device to fulfill his plans to overthrow the kingdom and the world.
When Robotnik launched his coup, he began rounding up the citizens of Mobotropolis and subjected them to the Roboticizer. The machine transformed its victims from flesh and blood Mobians into mindless, mechanical Robians that were completely subservient to Robotnik's will and were reduced to tireless, obedient slaves. For years, Robotnik dominated Mobius and terrorized its population, using Roboticizers to enslave most of the planet. After Robotnik was killed at the end of the First Robotnik War, the Robian population was freed from his control, although they remained trapped in a mechanical state.
When Robotnik's broken empire was revived by an alternate version of himself from a parallel universe, the Robian population was largely re-enslaved. This did not last, however, as an alien race called the Bem visited Mobius and de-roboticized the entire population (with the exception of Jules Hedgehog), restoring the Robians to their organic states and their free will. The de-robotization effect seemed to be permanent as Dr. Eggman attempted to re-roboticize several of his subjects only to find out that the Roboticizer no longer worked.
Years later, Eggman would launch Operation: Clean Sweep and use his new Death Egg's Cosmic Reset device to essentially "reset" the universe. This weapon only partially succeeded, however; reality and the timeline reasserted themselves, but the Genesis Wave did eliminate the Bem's de-robotization effect across Mobius to a degree. The Death Egg was equipped with a super-powerful World Roboticizer which, when activated, would release a roboticization wave across the planet, converting every organic life-form on Mobius into robots bent to Eggman's will. But before Eggman could fire the World Roboticizer, Princess Sally sabotaged the device and caused it to feedback on itself. This destroyed the machine, but still roboticized everything within its chamber. Thus, Sally was transformed into what Eggman would dub "Mecha Sally".
Post-Super Genesis Wave
In the altered timeline following the Worlds Collide event, the history of roboticizer technology is largely unchanged. As in the Pre-SGW timeline, the Roboticizer was invented by Professor Charles Hedgehog as a medical tool and was actually used as such. When Dr. Eggman launched his war against the Acorn Kingdom, Bunnie Rabbot was injured during an attack and had to have her arm and legs roboticized. Unlike in the Pre-SGW timeline, Eggman only made limited use of the Roboticizer himself, though it is unclear why. Supposedly he lost the ability to roboticize his subjects at some point, but was working towards restoring it when he launched the Death Egg.
Sonic the Hedgehog (SatAM)
In the 1993 animated series Sonic the Hedgehog, the origins of the Roboticizer were identical to the Archie Comics version. Sonic's uncle Sir Charles invented the technology only for Dr. Robotnik to steal the device and use it as his tool for enslaving the population of Mobius. Ten years into his reign, Robotnik had roboticized virtually all life on the planet.
At some point, the Freedom Fighters attempted to copy the software from the Roboticizer in Robotnik's fortress in hopes of developing a means of reversing the roboticization process. They eventually gathered enough material to build a prototype De-roboticizer and used it to restore Uncle Chuck and Bunnie Rabbot back to flesh and blood. Unfortunately, the effect wasn't permanent and both Chuck and Bunnie reverted back to their roboticized states.
In Sonic Underground, the Roboticizer's origins are never explained. While Uncle Chuck does appear in the show, there is nothing to suggest that he created the Roboticizer and it is speculated that Robotnik created the device himself.
Unlike other versions, the Roboticizer in Underground does not completely convert organic subjects into robots as parts of their original organic forms are still visible. Instead, the device seems to turn its victims into cyborgs, though they still lose their free will and become slaves to Robotnik. Robotnik does not subject all citizens to roboticization, however, and seems to reserve it as punishment for rebels and criminals as opposed to imprisonment.
Throughout the Sonic video games, Dr. Eggman has often turned living animals into Badniks. The process by which he does this has only ever been shown in Sonic Lost World where animals are placed within Badnik shells on an assembly line. In the same game, the Deadly Six seize control of Eggman's facility and kidnap Tails, intent on turning him into a robot. Tails is not placed inside a Badnik shell like other animals, rather he has pieces of a robotic exoskeleton attached to him.
In a promotional video for Sonic Forces, Dr. Eggman invites citizens to join the Eggman Empire and offers a free "robotomy" service, in which citizens are turned into robots. Whether or not this actually happens in the game's story is unknown, though no animals are contained within any of the Badniks that the player defeats throughout the game.