Sonic the Hedgehog 3 is a 1994 platform video game in the Sonic the Hedgehog series for the Sega Mega Drive/Genesis. It was developed in the United States by members of Sonic Team working at Sega Technical Institute, and was published by Sega, debuting worldwide in the first half of 1994. The game is a sequel to Sonic the Hedgehog 2 and follows on directly from the end of the game, in which Sonic defeated his enemy, Dr. Robotnik; crash-landing on a floating island, Sonic encounters new character Knuckles the Echidna, and must once more retrieve the Chaos Emeralds while also working to stop Dr. Robotnik from relaunching his ship, the Death Egg.

The game is closely tied to its direct sequel Sonic & Knuckles, as the two games were originally one until time constraints and cartridge costs forced the game to be split into two interlocking parts.

Main game

While improvements are present, the game is still very similar to the basic set-up of the original Sonic the Hedgehog game. The game still plays as a 2D sidescrolling platformer, with the player directing Sonic through levels and around obstacles within a time limit of 10 minutes. Like Sonic 2, players have the option of picking between Sonic, Tails, or both, with Tails being controlled by either the computer, or a second player if present.

The game is made up of six levels, each containing two parts with a boss at the end. When the game is cleared, players become able to play any level.

Characters now have unique abilities, performed by pressing the jump button a second time while in mid-air. Sonic can perform a split second "shield" move that provides both burst of protection and expands his attack range. Tails has the ability to fly in the air or swim underwater for a short amount of time before he gets tired and comes back down, allowing him to explore areas Sonic cannot. While flying, his tails can be used to attack enemies. Additionally, if a second player controls Tails, they can carry Sonic while flying. The game also introduces three kinds of shields; thunder, which protects against electricity and magnetically attracts rings, fire, which protects against fire attacks, and bubble, which allows its wearer to breathe underwater. When Sonic uses these shields, he can perform an additional skill based on his shield.

Hitting star post checkpoints while possessing 50 or more rings allows the player to access a bonus stage. This bonus stage is a bumper stage with a gumball machine that dispenses shields, rings, and extra lives.

Special stages

Special Stages can be entered by finding giant rings hidden throughout each stage. In these stages, players navigate a three dimensional space where the goal is to collect all the blue spheres in the level without touching any red ones. Collecting blue spheres transforms them into red ones, but if a player goes around the edge of a group of blue spheres at least 3x3 in size, all the spheres in that group will transform into rings, which can earn continues if enough are collected. Successfully completing these Special Stages earns the player a Chaos Emerald, which enables players to access the good ending if all seven are collected. Additionally, if Sonic collects all seven emeralds, he can transform into Super Sonic after collecting at least 50 rings. Additional emeralds known as Super Emeralds can be obtained if the game is locked on with Sonic & Knuckles, which enable Sonic and Tails to become Hyper Sonic and Super Tails with unique abilities.

Multiplayer

Competition Mode is a competitive mode in which two players, playing as either Sonic, Tails or Knuckles, race against each other through five laps on an endless level, unrelated to the levels played in the main game. During the game, players can collect items to either help themselves or hinder their opponent. There are three game types available: Grand Prix, in which all five tracks are playing continuously, Single Race, where a single track is chosen to race on, or Time Trial, a single player mode in which players try to clear the five laps in the quickest time possible.

Connection to Sonic & Knuckles

Sonic the Hedgehog 3 and Sonic & Knuckles were originally to be released as one game. However, due to time and money contraints, it was later split into two separate games. However, Sonic & Knuckles contained "Lock-on Technology", where the Sonic & Knuckles cartridge would be put in the Sega Genesis system, and then another game could be placed onto the top of the Sonic & Knuckles cartridge itself. When Sonic 3 is used in this manner, it enables the player to play through both games all at once. This features several additions to the games not available otherwise, such as small alterations to the levels, and being able to play through Sonic 3 levels as Knuckles, or Sonic & Knuckles levels as Tails.