Sonic the Hedgehog 2 (Genesis)

Sonic the Hedgehog 2
Developer: Sonic Team / Sega Technical Institute Publisher: Sega Platform: Genesis Released in JP: November 21, 1992 Released in US: November 24, 1992 Released in EU: November 24, 1992 This game has unused areas. This game has unused graphics. This game has unused music. This game has debugging material. This game has a notes page This game has a prototype article This game has a bugs page This game has a prerelease article

Sonic the Hedgehog 2 is the sequel to the first game. Sadly, a large number of interesting things were cut from the final version, such as the ever-famous Hidden Palace Zone.

Debug Mode

As in Sonic 1, Sonic 2 has a well-known debug mode:

• Go into the Options mode.
• In the Sound Test, select the following numbers in order, pressing C for each number: 19, 65, 09, 17 (September 17, 1965 is Yuji Naka's birthday). This accesses the Level Select.
• Press start to return to the title screen. When Sonic and Tails pop up, Hold A and press Start to bring up the Level Select screen.
• In the Level Select sound test, select the following numbers in order, pressing C for each number: 01, 09, 09, 02, 01, 01, 02, 04 (November 24, 1992 is the date of the game's US release).
• Choose any level, then hold A and press Start. Hold A until the level fully loads.

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 to enter placement mode. 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.
  • Press B to enable slow motion.
  • Press C to enable frame advance.

In addition, if you die, press B to enter placement mode before Sonic leaves the screen, and then press B at a safe spot to revive yourself. However, trying to place an object in this death state will freeze the game.

Unused Sprites

Artwork	Name	Description
	Barrier	Unused door barriers from Aquatic Ruin Zone.
	Unused Balkiry Frame	Unused frame of the Balkiry badnik from Sky Chase Zone, with landing gear deployed. It's possible that they were originally intended to take off from Wing Fortress as it passed by.
	Walking Turtle	Walking sprites of the turtles that pop out of the badniks in Sky Chase Zone. Normally you'll never see this, since the badnik never has the opportunity to hit the ground.
	HPZ Icon	Level Select icon for Hidden Palace Zone. It is not used in any version of Sonic 2, but does appear in Sonic the Hedgehog 3's level select, which contains level icons for the Sonic 2 levels.
	Laser	A large laser shooting through a spinning platform, intended for Wing Fortress Zone.
	Ring Platform	A weird platform made of rings, which can be placed in Mystic Cave Zone via debug mode. It moves back and forth depending on which side you stand on.
	Spinning Pole	Weird spinning pole that acts like a badnik - you can destroy it, and it can hurt you, but it doesn't actually move. Would have appeared in Wing Fortress Zone.
File:S2 static monitor.png	Static TV Monitor	A monitor which harms you when broken.

(Source: Sonic Retro)

Unused Music Track

In the sound test, song $10 is an unused song established to be the music meant for Hidden Palace Zone (see below). It is not in the Simon Wai prototype, where the 2-player Mystic Cave theme is used for Hidden Palace.

(Source: Sonic Retro)

Disc 2, Track 37 of the Sonic the Hedgehog 1&2 Soundtrack contains Masato Nakamura's original demo version of Hidden Palace Zone's music, but it doesn't loop and then fade out like the other Zone demo tracks; instead, towards the end of the track, the tune changes significantly and has a proper ending. This may suggest that the music was originally intended for some sort of cutscene, perhaps taking place in Hidden Palace Zone. Interestingly, this track is referred to as "STH2 Unused Song ~ Masa's Demo version ~", without specifying Hidden Palace Zone in the music track's title.

Unused Sounds

Some sounds are left over from Sonic 1. These sounds can be played from the sound test:

To do: Upload these sounds and confirm that they are unused

$29= Hit 'R', 'UP', and 'Down' block in Sonic 1 Special Stage

$31= Zapping sound from Scrap Brain Zone in Sonic 1

$3A= Hit colored diamond-shaped block in Sonic 1 Special Stage

$3D= Chain spike platform falling in Marble Zone from Sonic 1

$43= Warp to Sonic 1 Special Stage via giant ring at end of act

$49= Bonus point tag appearing at the end of a Sonic 1 act

Scrapped Zone Remains

The level slot containing Hidden Palace Zone in the prototypes actually retains the object layout, but the art and block mappings point to Oil Ocean Zone's 16x16 mappings, the level layout points to Oil Ocean Zone act 1, and the Badniks' code was removed. However the game still holds the original palette. By using Game Genie code ACLA-ATD4 and selecting Death Egg in the level select, you can see this for yourself. For the "Revision 00" version of the final, use ACLA-ATDR. This level uses track 10 of the sound test (otherwise unused) and Oil Ocean's debug item list.

The level slot containing Wood Zone in the prototypes also has something left in the final, albeit less than Hidden Palace: palette, object layout and music selection data. Accessing it via Pro Action Replay code FFFE10:0200 or Game Genie code ACLA-AECY and selecting Death Egg in the level select leads to an objectless (since Wood Zone was empty to begin with) Emerald Hill 1 with Wood's palette and glitchy collision. The debug item list only has rings and teleport monitors.

• 

  What's left of Hidden Palace Zone. Note the presence of a title card.

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  What's left of Wood Zone. Note the life icon displays Tails instead of Sonic.