Sonic the Hedgehog Genesis is a Game Boy Advance port of Sonic the Hedgehog, originally released for the Sega Genesis. It was released in November 2006 to celebrate the franchise's (and the original game's) 15th anniversary. There are several differences from the original game.
- Further reading: Sonic the Hedgehog (1991)#Gameplay
The game is divided into 7 zones that have 3 acts each (with the exception of Final Zone, which only has a single act.) The goal of the first 2 acts is to simply get to the end and run past the sign post. However, the third act always has a boss battle at the end. (Final Zone's single act is a boss battle). When running through the stages, there are various obstacles such as Badniks, Spikes, Lava and Water. Also, there are rings scattered throughout the stages. If Sonic gets hit without any rings, he loses a life. However, if Sonic gets hit while holding on to at least a single ring, he won't lose a life (he will however lose all of the rings he is currently holding). If Sonic collects 100 rings, he gains an extra life.
- The screen ratio has been reduced to fit the GBA screen and keep everything the same size.
- Sonic's "death" animation is only shown for a split second. Whenever the player loses a life, the drown animation is shown instead.
- A new "Anniversary mode" has been added where the player can use the Spin Dash, which was introduced in Sonic the Hedgehog 2, although there is an original mode that could be played without this feature.
- The music and some sound effects were remade.
- The gameplay and music are constantly out-of-sync, as seen in the credits medley.
- The game experiences significant lag and the frame-rate quality is poor.
- The Debug and Level Select modes have been removed, but an unlockable juke box room has been added.
- The game saves any zones/acts completed so that they can be replayed or continued, but does not save any Chaos Emeralds or the player's score.
- If the player quits the game without getting a game over, retrying can be selected at the menu screen so that the player can continue the game with any emeralds and score, and the player will start on the act he/she left off.
- Some bosses, like the Star Light Zone boss in Star Light Zone, can be damaged by jumping and hitting them, which wasn't possible in the original version.
Sonic the Hedgehog Genesis was universally panned by critics and gamers alike. Some of the most heavily criticized aspects include the extremely choppy framerate, poorly emulated physics, awful remixes of the music and the unbelievable number of bugs and glitches.