Source plot synopsis — includes the ending
Doctor Robotnik discovers mysterious birds called Flickies that live on an island in an alternate dimension. He learns they can travel anywhere using large rings, so he exploits them by turning them into robots to help him search for the Chaos Emeralds. Sonic arrives at the island only to discover the presence of Robotnik, and he is tasked with saving the Flickies and defeating his nemesis.
Sonic travels through the island, saving the Flickies and clashing with Robotnik in his various machines. If the player collects all the Chaos Emeralds, Sonic proceeds into a black void, where he engages in a final battle with Robotnik, who pilots a large robot. Sonic manages to destroy the robot's weapons and defeats Robotnik, freeing the Flickies. If the player fails to collect the Emeralds, Robotnik escapes with it in his possession.
Sonic travels through the island, saving the Flickies and clashing with Robotnik in his various machines. If the player collects all the Chaos Emeralds, Sonic proceeds into a black void, where he engages in a final battle with Robotnik, who pilots a large robot. Sonic manages to destroy the robot's weapons and defeats Robotnik, freeing the Flickies. If the player fails to collect the Emeralds, Robotnik escapes with it in his possession.
Sources and content license
Source and revision history ↗ · Adapted from Wikipedia contributors, Sonic 3D Blast. Section headings and formatting adjusted. · Content license