Sonic Chaos

In Sonic Chaos, players control one of two characters—Sonic the Hedgehog or his sidekick Miles "Tails" Prower—and must complete each of the game's six worlds in a quest to retrieve the Chaos Emeralds from the evil scientist Dr. Robotnik, who plots to use them to rule the world. Each world, referred to as "zones" in-game, is made up of three levels, called "acts", the third one consisting of a boss fight against one of Robotnik's henchbots, or Robotnik himself in the final zone. Levels are designed to allow the player to move as quickly as possible, and are largely based on those in its predecessor Sonic the Hedgehog 2.

The gameplay itself involves running through each level while collecting rings and defeating Robotnik's robotic minions; rings protect Sonic and Tails from being hit by an enemy or obstacle. Levels also contain small television monitors that can be smashed to reveal a power-up icon, which grant Sonic and Tails with unique abilities, such as speed shoes, a one-hit shield, and extra lives.

Sonic Chaos was developed by Japanese studio Aspect, being the second Sonic the Hedgehog game they produced, and published by Sega for the Master System and Game Gear. Chaos is largely based on the Master System version of Sonic the Hedgehog 2, and is thus considered a follow-up or successor to that game. Aspect used the experience it received for its work on the previous Sonic game while designing Chaos to make it more expansive and faster than its predecessors, in addition to improving the quality of the visuals. For the same reason, they were also able to make the game run faster. Chaos is both the first portable Sonic game and the first to feature Tails as a separate playable character with his own unique abilities.

Sonic Chaos was released for the Master System on November 23, 1993 exclusively to PAL regions, and for the Game Gear worldwide on the same day to coincide with the release of Sonic CD and Sonic Spinball as part of Sega of America's "Sonic Three on One Day" release strategy. In Japan, it was titled Sonic & Tails and was released four days earlier. The Game Gear version was included as an unlockable bonus in Sonic Adventure DX: Director's Cut (2003) as one of the eleven unlockable Sonic Game Gear games, and in Sonic Mega Collection Plus (2004) for the PlayStation 2, Xbox, and Windows. In 2009 the Master System version was digitally released for the Wii's Virtual Console worldwide.

In the United States, it was the top-selling Game Gear game in January 1994.

Sonic Chaos initially received a positive response from publications. The four reviewers of Electronic Gaming Monthly commented that the Game Gear version retains all the elements that made the 16-bit Sonic games fun to play. They also praised the graphics and the ability to play as Tails. Sonic Chaos was awarded Best Game Gear Game of 1993 by Electronic Gaming Monthly.