As usual Dr. Robotnik has captured all of the Chaos Emeralds. Unfortunately for him, an accident in the testing phase of his new ultimate weapon, the Atomic Destroyer, scatters the Emeralds back across the island. While Sonic and Tails are out to retrieve them, they are cut short by Knuckles the Echidna. Robotnik has already reclaimed the yellow emerald, and he's duped the island guardian into believing Sonic and Tails are out to steal the stones.
Meanwhile, a sneaky treasure hunter named Nack the Weasel (Fang the Sniper in the Japanese version) is taking advantage of the commotion to take the Emeralds. He does not know of the true power of the Emeralds, but he does know the large, pretty gems would fetch a high price on the market. Now it's a mad four-sided race for the Chaos Emeralds.

 Gameplay

Gameplay of Tails in the first level, Great Turquoise Zone.

While the first few Sonic games for the Game Gear were simply ports of the Sega Master System versions, and lacked some of the elements found in the Sega Genesis series, this exclusive Game Gear game was a lot larger in size than its predecessors. Gameplay gave an experience very much in keeping with the Sonic games of the Genesis.

This is the first Sonic game in which the player does not lose all of his rings after getting hurt. In this specific case, during any act of Zone 1, 2, or 6, or the first act of any other Zone, each hit will take away 30 rings. In the second act of Zone 3, 4, or 5, 50 rings will be lost.

The choice is given of playing as either Sonic or Tails. Sonic has the ability to do the Strike Dash/Super Peel Out as he does in Sonic Chaos" that gives him a speed burst and temporary invincibility. Tails has the ability of flight. The enemies are Dr. Robotnik, a laughing Knuckles and the ambitious treasure-hunter Nack the Weasel, first-introduced in the series, who only appears in the Special Stages to keep aside the Chaos Emeralds.

 Zones

There are six stages, each with three Acts. The third Act is merely a short course (with a small cache of Rings to pick up) followed by a boss, one of Robotnik's powerful robot creations. The doctor himself doesn't show up until the final stage. Keeping with tradition, there are 5 unique special stages to access in the game. By collecting 50 rings and breaking open the "Chaos Emerald" item box, a portal appears which leads to the Special Stage. The first, third and fifth stages are giant mazes with a countdown timer. The timer can be boosted with "Stopwatch" item boxes scattered throughout, but it never exceeds one and a half minutes. The second and fourth Special Stages involve flying the Tornado aeroplane to collect rings and avoid bombs. At the end of every Special Stage, Nack shows up and attacks to protect the Chaos Emerald. Clearing all 5 Special Stages unlocks the "good" ending.