Robotnik learns that the most powerful gemstone -- able to create life itself -- is located in Prehistoric Times.
Robotnik timetravels back to Mobigypt, makes himself a pharoah, and enslaves everbody in an effort to find the gemstone of immortality.
Robotnik goes back to medieval times, and enlists the help of Merlink the Magician to get his gemstone.
When outlaws chase a sheriff out of a western town, Sonic takes over. But the outlaws are robots built by Robotnik. And when they capture a pretty possum of a saloon girl, Sonic meets Robotnik for a showdown.
When Robotnik puts a meteor on a collision course with a village, Sonic is forced to compete in the Robolympics to save the village. After a series of wild, booby trapped events, Sonic is victorious.
A captain of the Queen's guard is captured before he can reach the secret rendezvous where he was to meet Queen Aleena.
Robotnik announces that he will marry Queen Aleena in a plot to become the king of Mobius.
Sonic, Manic and Sonia find an abandoned baby in an alley and begin to look for the baby's parents. Manic becomes very fond of the child.
Sonic becomes aggravated that maybe their efforts of fighting for freedom seem pointless. Sonia suggests that they go to the Oracle for advice.
As Sonic begins to chow chili dogs for a snack, he finds a message in the sack from his mother urging him to head to Speedster Island.
Santa Claus has made an announcement - he is retiring and has picked the perfect successor - "Robotnikclaus"! Sonic and his sister resolve to persuade Santa to return and set Christmas straight. When the two track down the Santa who made the announcement, they discover he is just a phony robot and the real Santa Claus is being held prisoner.
In Part II, Sonic and Sally steal the Roboti-sizer plans, stop the Destroyer from polluting the Great Forest and save Little Sonic, Little Sally and Dulcy's mother, Sabina.
After a disastrous failed mission, Sonic laments that they can't go back and prevent Robotnik's take-over. Dulcy tells them they can and takes Sonic and Sally to the Floating Island where they find the "Time Stones".
Sonic attempts a solo rescue to prevent prisoners from being roboti-sized and is hit by a Memory Scrambler that erases short-term memory.
The Freedom Fighters, with new addition, Dulcy, develop a De-Roboti-sizer and try it out on Bunnie. It's a success and, against Sally's wishes, Sonic battles Robotnik's newest weapon, a Virtual Reality Shriek-Bot.
Sonic reluctantly takes Tails with him to the Big City to find some cotter pins for the Freedom Fighters catapults. While in the City, Sonic is nearly eaten alive by his old dog Muttski, now a roboti-sized guard dog in the Junk Heaps
Tails brings a new friend home to Knothole - a baby Terra-Pod who has strayed from the herd that is currently migrating. Sonic, Sally, and some of the other Freedom Fighters return the Baby-T to its mom and the rest of the herd.
Robotnik severely upsets the ecosystem above and below the surface, when he sends explosive, Robotnik snake probes drilling deep under ground in search of oil lakes.
Santa Claus has made an announcement - he is retiring and has picked the perfect successor - "Robotnikclaus"! Sonic and his sister resolve to persuade Santa to return and set Christmas straight. When the two track down the Santa who made the announcement, they discover he is just a phony robot and the real Santa Claus is being held prisoner.
Sonia discovers that the watch she received from her friend is actually a monitoring device for the Robotnik Intelligence Agency.