In the arcade game SegaSonic the Hedgehog, Sonic was captured da Dr. Robotnik, along with Mighty the armadillo and raggio, ray the Flying Squirrel. Sonic teamed up with the other two and they traveled to escape Eggman Island, which was covered with traps.
In the end, Robotnik self-destructed the island, but Sonic, raggio, ray and Mighty escaped just in time. However, the doctor escaped Sonic once again.
Time Traveling Hedgehog:
Sonic was solo once again for Sonic CD (1993), in which he went to Little Planet while it was at near Sonic's homeworld in order to explore it. However, his goals changed once he saw his arch-nemesis having taken over the entire planet, leaving Sonic to liberate it of the scientist's control.
Shortly after his arrival, Sonic met a female hedgehog named Amy Rose, who was on the planet in hopes of meeting him. However, only moments after she met him, she was captured da Metal Sonic, Sonic's second, robotic doppelgänger.
Using his unrivaled speed, Sonic managed to travel through time and ensure a good future for the Little Planet.
Near the end of his adventure, Sonic encountered Metal Sonic and the doctor once again, having a race with the robot on the Stardust Speedway. In the ensuing victory of Sonic's, the Eggman managed to accidentally destroy his own creation.
Sonic went on to defeat the doctor in a final battle in the Metallic Madness, after which Sonic rescued Amy while the doctor's bases began exploding and were literally crumbling away. The Little Planet went on mostra Sonic's face in a doccia of light before seemingly warping away from Earth, while leaving many new fiori grow around the area it floated above.
Eggman, on the other hand, seemingly managed to sneak a Time Stone off the Little Planet, but Sonic spotted him and managed to put an end to his current schemes da using his Spin Dash to shoot a rock in the direction of his flying machine, causing it to explode.
It is not known what happened with the Time Stone in question.
After that, Sonic went on his adventuring ways around the world.