Sonic the Hedgehog (Genesis)

From The Cutting Room Floor
Jump to: navigation, search

Title Screen

Sonic the Hedgehog

Also known as: Baramdori Sonic (KR)
Developer: Sonic Team
Publishers: Sega (JP/US/EU), Samsung (KR), Tec Toy (BR)
Platform: Genesis
Released in JP: July 26, 1991
Released in US: June 23, 1991
Released in EU: June 23, 1991
Released in KR: 1991
Released in BR: 1994

EnemyIcon.png This game has unused enemies.
GraphicsIcon.png This game has unused graphics.
ItemsIcon.png This game has unused items.
DebugIcon.png This game has debugging material.
SoundtestIcon.png This game has a hidden sound test.
LevelSelectIcon.png This game has a hidden level select.
RegionIcon.png This game has regional differences.
Carts.png This game has revisional differences.

PrereleaseIcon.png This game has a prerelease article

Sonic the Hedgehog is more or less the definitive game of the Genesis in the early 1990s and introduced the world to Sega's new mascot.


Level Select

Sonic The Hedgehog Genesis Level Select.png

One of the most well-known codes in gaming history: press Up, Down, Left, Right on the title screen, then hold A and press Start. In the original revision, the level order is different from the order in normal gameplay.

Green Hill Zone Green Hill Zone
Labyrinth Zone Marble Zone
Marble Zone Spring Yard Zone
Star Light Zone Labyrinth Zone
Spring Yard Zone Star Light Zone
Scrap Brain Zone Scrap Brain Zone
Final Zone Final Zone

Debug Mode

Another well-known code. While Up, C, Down, C, Left, C, Right, C is the most common version, a shorter version is C, C, Up, Down, Left, Right. The main requirement for the code is pressing C twice before the final input of Right. After entering the code, press Start while holding A and continue holding A until Sonic appears in the level.

To activate Level Select and Debug Mode, simply enter the Level Select code, push any direction on the D-Pad after the ring sound, then enter the Debug Mode code.

From here, you have access to a variety of things:

  • Invincibility
  • Infinite Time
  • Debug Coordinates (in place of score)
  • Sprite Counter (in place of time)
  • Placement Mode: Press B during gameplay. From there...
    • Press A to move forward one object.
    • Hold A and press C to move backward one object.
    • Press C to place the object.
  • Pause Options: press A to go back to the title screen, B to enable slow motion, or C to enable frame advance.

Unused Sprites

Special Stage

These can be seen in normal gameplay by falling out of a Special Stage using Debug mode.


Labelled as Zones 1-6, possibly used in Special Stages to mark which one you were in.


1 Up icon for Special Stages. This was found in the manual, but doesn't appear in the game. It is actually fully coded and functional, and collecting it will grant you an extra life.


A W block. Used in Special Stages, still have no idea what it did.


These are visible if you fly over the goal in debug mode, as the end-of-level art loading routine isn't executed and the goal art is written over the top of the art for the monitors.

Sonic1gen Tv eggman.png

A Robotnik monitor. Possibly would have hurt Sonic, like in Sonic 2 and 3 & Knuckles.

Sonic1gen Tv goggles.png

An image of Sonic's unused goggles, leading some to believe it was originally a powerup.

Sonic1Gen Statictv.png

A static monitor, used as a default for invalid object IDs. Scrap Brain Zone contains a number of these (apparently a victim of changing object allocations - the subtypes work perfectly if these are changed to solidity objects) which emit various glitched tiles when broken.

Sonic1Gen tv super.png

This monitor also appears in the Sonic CD Prototype 510, essentially giving the player a speed boost and invincibility.


Sonic1Gen Standair.png

Sonic gulping air. Likely used for the air bubbles found in Labyrinth Zone, and Scrap Brain Zone's third act.

Sonic1Gen Needair.gif

Sonic holding his breath. Possibly used for when the player was close to drowning.

Sonic1Gen Slide.gif

A sliding sprite. Similar to those used in Sonic CD.

Sonic1Gen sonicvictorypose.png

Seen in earlier development pictures. Apparently a victory animation used after passing the goal.

Sonic1Gen Spin.png

Spin Dash-like sprites. There's a routine which would change Sonic's sprite to one of these, but it's unused.

Sonic1Gen Falling or shrinking.png

Shrinking, maybe falling, sprites for Sonic. No idea how these would've worked.


Green Hill Zone

Sonic1Gen sonicwreck.gif

This checkered ball, seen in early screenshots, and part of the Green Hill Zone boss in the final. It would've, originally, been its own object, and crashed through walls that Sonic couldn't break through. The checker ball can still be viewed via debug mode, but cannot be placed.

Sonic1Gen GHZTotem.png

Two faces, possibly from an earlier point in development. Their true palette isn't in the game anymore. They are simply earlier versions of the Green Hill Zone decorations. They can be also seen in the Sonic 2 Nick Arcade prototype in Green Hill Zone, on the glitched Crabmeats and the Act 3 boss.

Sonic1Gen Missingghztiles1.gif

Unused tiles from the Green Hill Zone. Later reused in the 8-bit version.

Marble Zone

Sonic1Gen Sidespike.png

A horizontally-oriented spiked thingy. A fully functional but completely unused object exists for these.

Spring Yard Zone

Sonic1Gen Letsgo.png

A cut sign from Spring Yard Zone.


Sonic1gen Burrobot1.png

A Burrobot, facing downwards.

Star Light Zone

Sonic1Gen Light.gif Sonic1Gen Light2.gif

Unused lights from Star Light Zone.

Sonic1Gen Machine2.gif Sonic1Gen machinparts.png

Also, unused machinery scenery from the same level.

Final Zone

Sonic1Gen Robotniklegs1.png

The sprite on the left shows the legs of Robotnik's vehicle, which are impossible to see ingame.



A rosebud that acts like a bumper. This can be placed in the Special Stage and ending scene. The palette is lost.

Press Start Button


These tiles, which would appear on the title screen, don't show due to a programmer's goof. Strangely it will appear on Japanese systems after viewing the invisible credits.

Splats the Bunny


An unused Badnik intended for the Scrap Brain Zone. Notable, in that appeared in lots and lots of promotional material before meeting the ax. No idea if this is the intended palette or not.



Unused goggles poses. Assumed to be related to the goggles monitor, but may have just been used to show that Sonic was underwater.

Sonic1MDSonicgoggles Run.gif

How it looks assembled.

Unused Eggman Graphics


No idea, possibly an unused or cut ending sequence.

Invisible Credits


Credits that are hidden on the Sonic Team Presents screen, and completely unseen in every region outside of Japan. If you have a Japanese Megadrive, or switch the region to Japanese, you can use the code C, C, C, C, C, C, Up, Down, Down, Down, Left, Right, which should make a ring noise, then when the demo starts, enter Down + A + B + C to turn the screen's background to white, making the text visible when the demo finishes. This code does not work in the Sonic Classics version.

The credits translate to:

Position Person
Program Yuuji Naka
Plan Hirokazu Yasuhara
Design Naoto Ooshima
Jina Ishiwatari
Rieko Kataoka
Sound Produce Masato Nagamura
Sound Program Hiroshi Kubota
Yukifumi Makino

Misplaced Enemies

Sonic1 ghz2 crabmeat.png

In Green Hill Zone, there are multiple misplaced enemies such as this Crabmeat in Act 2 at coordinates 10D0 0370, under the section with the moving pillars and spikes, just before the checkpoint. They cannot be seen in gameplay, as they're always placed such that they instantly fall into the abyss and disappear - the Crabmeat is particularly amusing in that it's already below the level of the screen.

Revisional Differences

To do:
  • Should we include the differences in the Mega Collection bonus edit (most notably the so-called "spike-bug") since it's technically a modified Mega Drive ROM, even though no evidence of official cartridge release exists? Should we also mention the Sonic Jam edition on top of that, which implements the unused skidding effect and includes spin dash/"spike bug" toggle?
  • 3D Sega Classics version differences: spin dash, International/Japanese version toggling, Level Select available as toggle in Special menu...

A revision (commonly known as REV01) was silently released, which is more common in the Asian market. Most compilations and re-releases include this altered version. Below are the changes:

  • The game's background deformation and screen drawing routines were given significant overhauls. As a result, the clouds in Green Hill Zone and on the title screen now scroll from right to left (common in most depictions of Green Hill in the series) and the water in Labyrinth Zone/Scrap Brain Zone Act 3 has been given a ripple effect, similar to that of Sonic CD.
  • The level select was rearranged. In the initial release, the Zones were listed in a pre-release order that doesn't represent the final game.
  • There are more changes if the game detects whether it is being played on a Japanese console. Previously, it disabled the Debug Mode but enabled the hidden developer credits - the revision provides new level select and Debug Mode codes as well.
  • The points system was slightly altered: extra lives are now gained every 50,000 points, and the final boss now awards 1,000 points in defeat. Previously extra lives were not acquired upon reaching any particular point total and the final boss awarded no points at all.
  • Minor programming changes of certain properties such as Caterkiller's nuances, lamppost / game over and drowning music exist.
  • Generally, the game code is tighter, more efficient, and removed unnecessary remnants like certain unused sprites.
  • Holding buttons during the attract mode and ending demo sequences will not cause Sonic to miss jumps.

Labyrinth Zone's Extra Ring

Placing single rings is normally an unaesthetic thing to do.

There is one extra ring in Labyrinth Zone Act 1 of Revision 01. After the player presses a button near the two rising platforms, a platform spawns above, something few people know about. It's possible to reach this platform with a well-timed jump, and if the player rides on it, it'll take them to an alternate path which may have an extra ring. With this extra ring, it is possible to collect 50 rings (and so access the special stage) while taking this shortcut.

(Source: Sonic Retro)