Sonic 3D Blast is a game in the Sonic the Hedgehog series for the Sega Genesis and later released for the Wii Virtual Console. As Sonic, the player embarks on a journey to save the Flickies, birds enslaved by Doctor Robotnik. The player must guide Sonic through a series of themed levels to collect Flickies and defeat Robotnik. Though it retains game mechanics from the prior Sonic games, Sonic 3D Blast is differentiated by its isometric perspective, with pre-rendered 3D models converted into sprites.
The concept for Sonic 3D Blast originated during the development of Sonic the Hedgehog 3. Most of the programming was outsourced to the British studio Traveller's Tales, as the Japanese Sonic Team staff was preoccupied with Nights into Dreams. Development lasted eight months, and the team drew inspiration from Donkey Kong Country and Sonic Labyrinth.
Sonic 3D Blast is a platform game presented from an isometric perspective. Players control Sonic the Hedgehog, whose goal is to save the Flickies, collect the seven Chaos Emeralds, and defeat Doctor Robotnik and his robot army. Sonic retains most of his abilities from prior games: he can jump and spin in mid-air to defeat robots or hop on platforms, perform a spin-dash on the ground to gain speed, and collects rings as a form of health. Sonic can also collect power-ups, such as elemental shields, speed shoes, or invincibility, by breaking television monitors containing them.
The game is split into several levels called zones. Every zone has three acts: two standard levels, where the player must collect Flickies by defeating robots in order to proceed; and a boss fight against Robotnik, without any Flicky-collecting involved. In normal levels, once the player collects all five Flickies from each section of an act, Sonic is either further advanced into the act, or taken to the next act. If Sonic and the following Flickies are hit by an obstacle or enemy, the Flickies and the rings Sonic collected will scatter. Each individual Flicky's color determines its behavior: blue, pink and orange Flickies make an effort to find Sonic, while green and red Flickies wander off at random; the latter even jumping about, making them harder to re-collect. Sonic starts the game with four lives; if he is hit with no Flickies or rings in his possession, he will lose a life. Losing all lives results in a game over. Lives can be replenished by collecting a 1-up or collecting ten Sonic-shaped medals.
As with the previous games, Sonic 3D Blast includes "special stages", in which the player collects Chaos Emeralds. Obtaining all seven Emeralds allows the player to play the final boss battle and discover the true ending of the game. To access these stages, the player must find one of Sonic's friends (either Tails or Knuckles the Echidna) hidden within a level, and stand next to them with at least 50 rings collected. Doing so allows the player to exchange the rings in order for the chance to play the game's special stage. During special stages, the camera shifts to behind Sonic as he runs down a preset path and must collect rings while avoiding obstacles that, when run into, make him lose rings. A certain number of rings need to be obtained at certain checkpoints to continue through the stage, and ultimately be able to make it to the end in order to receive a Chaos Emerald. Collecting all seven Chaos Emeralds also allows the "Final Fight" level to be played, consisting of a final boss fight and the good ending of the game.
Doctor Robotnik discovers mysterious birds called Flickies that live on an island in an alternate dimension. He learns that they can travel anywhere using large rings, so he decides to exploit 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 in their possession.