Sonic the Hedgehog 3/Hidden content

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Level select + Debug mode

Right after the Sega logo's screen darkens and Sonic starts jumping towards the screen, quickly press . This code is notoriously hard to do, due to the weird frame windows, but if performed correctly, the Ring collection sound will play. In the Sonic Jam version of the game the code is entered on the title screen and no precise timing is required. Press twice (or once) to see a "Sound Test" option on the title screen.

An alternative way to unlock the level select, which can be performed on real hardware, is to activate the level select in Sonic the Hedgehog 2, then remove the Sonic 2 cartridge without turning the power off, insert the Sonic 3 cartridge, and reset.

Pressing on the level select screen increments a counter that determines the players' characters in the Competition mode Zones, with the first controller incrementing the left counter and the second counter incrementing the right:

• 00 - Sonic
• 01 - Tails
• 02 - Knuckles

This cheat also enables debug mode, which is activated by holding and pressing to choose a level. A Game Genie code for accessing the level select is also available. During gameplay:

• Press + to cycle through all mapping frames of the character when in normal mode.
• Press to toggle normal and debug mode.
  • Press to advance forward through the debug object list.
  • Press + to advance backwards through the debug object list.
  • Press to place the selected object at the current coordinates.
• During pause press to fade to black and restart from the level select screen.
• During pause press and hold to enable slow-motion (this proceeds at half-speed for as long as the button is held down).
• During pause press to advance one frame.
• Current coordinates are designated by the top line of hex digits in the HUD.
• Viewport coordinates are designated by the bottom line of hex digits in the HUD.

The check for the sound test code from the 1993-11-03 and Sonic 3C 0408 prototypes (01, 03, 05, 07) remains, but as debug mode is enabled with the level select it is rendered pointless here.

All Chaos Emeralds

Play sounds 02, 04, 05, 06 in the sound test. A Chaos Emerald sound will confirm correct entry.

Eighth Special Stage

Go the level select, play any sound between 00-07, and press + on the "Special Stage 2" selection to choose a particular Special Stage. Playing 07 will load an eighth Special Stage layout that is not used in normal play.

This Special Stage consists of a long spiral towards the center. There are no Rings to collect, which will make getting a Perfect Bonus impossible. Clearing this Special Stage awards a grey Chaos Emerald that has no special effect in-game, and does not appear on the results tally in any form other than a score increase.

Night mode

Enable the level select, then select a Zone and press +.

Unused content

Art

Art	Description
	Sonic in his signature "waiting" pose, but instead of pointing towards the direction he's facing, he falls asleep from boredom instead. Never used in-game. Sonic Origins uses this animation when Sonic has been left idle for nearly a minute, as does the Game.com version of Sonic Jam. A modified version of this animation exists in Sonic X for the Leapster.
	Sonic whistling. Not used in-game. Speculation reveals that this animation may have been paired with a "Help-Item" mentioned in an article from German magazine Sega Magazin. Sonic would have broken the monitor, used the whistling animation, and then Tails would fly in from out-of-screen to carry Sonic around as he pleased, similar to a second player controlling Tails while holding the first player. A whistle sound which is probably related to this can be heard when breaking S-monitors and at the beginning of Doomsday Zone. It was also used in the Game.com version of Sonic Jam.
	A black & white version of Sonic's death sprite, similar to the one seen in the previous two games. It's still not used.
	These animations would later be used for Flying Battery Zone's monkey bars in Sonic & Knuckles.
	These animations would later be used for Knuckles' wind trap in Sonic & Knuckles.
	These sprites would later be used for swinging off the poles in Mushroom Hill Zone in Sonic & Knuckles.
	These sprites would later be used for cascading down the towers in Sandopolis Zone in Sonic & Knuckles.
	Leftover animation from the continue screen in Sonic 2.
	Knuckles on the Data Select screen. This can be seen when trying to play as Knuckles in Sonic 3.
	Leftover sprites for Knuckles on the continue screen. Later used in Sonic & Knuckles.
	Knuckles text which would have been used upon Act and Special Stage completion. This can be seen in-game by making a save file for "Knuckles".
	Knuckles's life icon also remains in the game, albeit unused. It would later be used in Sonic & Knuckles.
	Unused Gliding/Climbing animations exist for Knuckles in two-player mode, even though he doesn't have the ability to glide or climb while in two-player.
	Smaller rendition of the Death Egg. It seems to be part of a Death Egg hologram projector which was also unused in Sonic & Knuckles.
	Diagonal frames of the Penguinator from IceCap Zone. These can be seen for a split second if they are placed on the large hill at the beginning of Act 1 using debug mode.
	Unused running frame where Eggman has a different facial expression.
	Eggman sprites normally used for the Barrier Eggman mini-boss.
	Eggman sprites used for the Hang Mobile. While these would be used in Sonic & Knuckles, one of the sprites would remain unused during the actual boss fight due to a coding error.
	Graphics for a shadow found among the graphics for the Tornado in Angel Island Zone. This may have appeared under the Tornado as it approached the island.
	A button-like object that is loaded early on in the space used for the burning Angel Island Zone stage graphics.
	This lightbulb is normally found in Carnival Night Zone Act 2 when Knuckles switches off the power, but it has an unused function: if it becomes submerged in water, it will explode and display the sprite seen on the right. Since it isn't placed anywhere that gets submerged in water, it is never seen in normal play, requiring the player to use debug mode to place it in water and see it there.
	The teleporter normally used by Knuckles at the start of IceCap Zone Act 1.
	A large ice boulder that appears to have been meant for IceCap Zone.
	This sprite is actually used by the Beam Rocket, but it is obscured and cannot be seen.
	The bomb used by Eggrobo in cutscenes in Sonic & Knuckles and Sonic 3 & Knuckles.
	The attachment on the Egg Mobile which Eggrobo would use to drop a bomb on Knuckles in Launch Base Zone Act 2. This graphic was used in the Sonic 3C 0408, Sonic 3C 0517 and Sonic & Knuckles 0525 prototypes, but is not used in the final Sonic 3 & Knuckles.
	Graphics and palette data for the yellow spheres from the Sonic & Knuckles Special Stages. While they are loaded every time the player enters a Special Stage, coding doesn't exist for them yet and thus cannot be encountered.
	An unused Data Select icon for Flying Battery Zone, from the days when Sonic 3 and Sonic & Knuckles were to be a single game. The Sonic 3 icon can be found in both the PC and Mega Drive versions of Sonic 3, and can be viewed by hacking the SRAM for the game to access level slot $04, or by using the PAR codes 00C324:601E and 00C338:6002 to view the icon in a completed game save slot while scrolling through the levels. The Sonic 3 & Knuckles icon is displayed here for comparison.
	Icons originally used to track the players' progress in Competition mode, leftover from the November 3rd prototype.
	An unknown graphic that may resemble some kind of medal for Competition mode. No known palette exists for this graphic.
	Leftover signpost sprites from the November 3rd prototype that remain in both the final game and Sonic and Knuckles.

Objects

Placeable in edit mode

Art	Description
	An "S" monitor, which transforms Sonic into Super Sonic when broken.
	A breakable wall in Angel Island Zone Act 2, which can only be placed with debug mode and is destroyed with a Spin Dash on the ground. A similar object is used as a wall that is opened with a switch.
	A button of unknown purpose. It can be placed in either Act of Carnival Night Zone via debug mode, but it doesn't appear to do anything. Also unused in Sonic 3 & Knuckles.
	An unknown Ring-like object that appears to spawn slope collision when placed. It is placeable in Carnival Night Zone.
	A glowing block that can be placed in either Act of IceCap Zone via debug mode. Jumping on it destroys it like the ice blocks. Also unused in Sonic 3 & Knuckles.
	A set of spikes for Competition Mode. However, spikes do not appear in any of the five Zones, but they can be placed with debug mode.

Red revolving spheres

This is a spinning mass of red spheres, placeable by debug mode in the first part of Angel Island Zone Act 1. The spheres look similar to those appearing in the game's Special Stage. When it is placed, many palette and VRAM complications occur in the level, and the game slows down considerably. It can be manipulated with the second controller:

• — Rotates the object vertically.
• — Rotates the object horizontally.
• / — Moves the object up or down.
• / — Changes the object's size.
• — Rotates the object sideways.
• — Toggles automatic rotation.

This object was originally used to test the 3D mechanics of the Special Stage in the November 3rd prototype.

Others

Art	Description
	A blank monitor that harms the player when broken. Set a monitor subtype to 00 to view it in-game.
	Knuckles' version of the Drill Mobile for Marble Garden Zone Act 2. It functions identically to how it does in Sonic 3 & Knuckles, except it is invincible.
	A spring that moves up and down, which was intended for Flying Battery Zone. Its object ID is 3D.
	Blaster, who is intended for Flying Battery Zone with leftover code, and can be placed with debug mode if the game is hacked to load Flying Battery Zone. Its projectiles can be destroyed like regular Badniks.
	Technosqueek, who is intended for Flying Battery Zone with leftover code, and can be placed with debug mode if the game is hacked to load Flying Battery Zone. For some reason, placing a sideways one will crash the game.
	Owing to its removal, Flying Battery Zone still retains its bosses within the ROM. Gapsule is nearly identical to its appearance in Sonic & Knuckles, albeit with a slightly different palette. It can be found by hacking the game to load Flying Battery Zone Act 1 and exploring the level.
	The Barrier Eggman sub-boss for Flying Battery Zone Act 2. It functions nearly identically to how it does in Sonic & Knuckles, except it has no sound effects. For reasons unknown, it is not actually placed in Act 2.
	The Hang Mobile boss for Flying Battery Zone Act 2. It is slightly different in terms of coding and has no sound effects.
	An unused Eggman object discovered by Nemesis that isn't called by any routine. It appears to be nothing more than Eggman flying away towards the horizon. It may have been intended for the cutscene after defeating the Big Arm fight as the object is located between the LBZ2 bosses and the falling Death Egg in the ROM, and its animation somewhat fits with the way the Death Egg falls, however the Death Egg noticeably falls on the opposite direction of where Eggman goes in the actual game. This can be re-enabled using the PAR code 05165A:04F2. The object and its associated sprites were later used in Sonic Origins.
	A flashing S gumball for the Gumball Machine Bonus Stage, which can also be seen hidden behind the other gumballs inside the machine. If the gumball object's subtype is manually set to 08, it'll use a unique item collection routine that sets a RAM address to 07, which has nothing to do with super transformations and is cleared on level load.
	A glitched platform that appears to belong to Launch Base Zone, as its graphics appear to be the most correct there. Its object ID is 12, and its offset is $1C6A0.
	A seesaw-like cannon that locks the player in the center of the object, and propels them extremely far when pressing a button. Its object ID is 1A, and its offset is $1DFCE.
	A strange, spinning object that hurts the player when jumped on, and swings when hit from underneath. Its object ID is 1C, and its offset is $1E6C6.
	A Launch Base Zone platform that can be grabbed from underneath. Its object ID is 1D, and its offset is $1C228.
	An object originally used in Sonic 1 and Sonic 2 to damage the player when they touched lava, except it no longer functions here. Its size can be changed by altering its subtype. Its object ID is 27.

Audio

Music

Audio	Description
	Flying Battery Zone Act 1; sound ID 09. The loop point in the "echo" track of the lead instrument is set slightly later than the rest of the tracks. This leads to the song falling further and further out of sync each time the song loops. This was fixed in Sonic & Knuckles and Sonic 3 & Knuckles.
	Flying Battery Zone Act 2; sound ID 0A.
	Mushroom Hill/Valley Zone Act 1; sound ID 0F.
	Mushroom Hill/Valley Zone Act 2; sound ID 10.
	Sandopolis Zone Act 1; sound ID 11.
	Sandopolis Zone Act 2; sound ID 12.
	Lava Reef Zone Act 1; sound ID 13.
	Lava Reef Zone Act 2/Hidden Palace Zone; sound ID 14.
	Sky Sanctuary Zone; sound ID 15.
	Death Egg Zone Act 1; sound ID 16.
	Death Egg Zone Act 2; sound ID 17.
	Sonic & Knuckles Act 1 Boss; sound ID 18. Not totally unused as it can be heard while fighting the Big Shaker or Screw Mobile by jumping out of the water after the drowning music starts.
	The Doomsday Zone; sound ID 1A.
	Glowing Spheres Bonus Stage; sound ID 1B.
	Slot Machine Bonus Stage; sound ID 1D.

Sound effects

Many of these sound effects would see use in Sonic & Knuckles and Sonic 3 & Knuckles, though some of these sounds would also be unused there.

Audio	Description
	Sound ID 3A and 71. Shield sound leftover from Sonic the Hedgehog 2
	Sound ID 40. Unused; an electric zap heard among the Shield sound effects. This sound would later be used for the Thunder Shield in Sonic Generations and Sonic Lost World, and for the Phantom Egg's barrier in Sonic Mania.
	Sound ID 53. Laser charging sound, used for the Barrier Eggman mini-boss and the jumping spike balls in Lava Reef Zone Act 2.
	Sound ID 54. Laser firing sound, used for the Barrier Eggman mini-boss.
	Sound ID 55. Used for the pushable bricks in Sandopolis Zone as they ride across small black wheels.
	Sound ID 5A. Unused; sounds like something revving up. This would later be used in Sonic 3D: Flickies' Island.
	Sound ID 5C. The sound of Mecha Sonic short-circuiting after its defeat.
	Sound ID 69. Used when pushing bricks in Sandopolis Zone.
	Sound ID 6B. Unknown, possibly unused; sounds like a higher-pitched version of the sound heard when hitting an R, Up or Down block in the Sonic 1 Special Stage.
	Sound ID 6D. Unused; sounds like a door closing.
	Sound ID 7A. The sound of the Hot Mobile emerging from lava.
	Sound ID 7C. Used by the magnetised platforms in Flying Battery Zone.
	Sound ID 7D. Unused; sounds like mild rattling.
	Sound ID 84. Unused; sounds like something charging up. Only seems to be referenced in some Zone with a high level ID which is composed of garbage data.
	Sound ID 85. Unused; sounds like it would have been used in cooperation with sound 84.
	Sound ID 87. The sound for bouncing on a mushroom in Mushroom Hill Zone.
	Sound ID 88. The sound for operating the pulley lifts in Mushroom Hill Zone.
	Sound ID 89. The sound used by the Jet Mobile's weather-altering satellite dish.
	Sound ID 8A. The sound the Hyudoro from Sandopolis Zone make when they vanish.
	Sound ID 8B. The sound of Hey Ho chopping a log.
	Sound ID 8C. The sound of Hey Ho struggling to chop a log.
	Sound ID 8D. Unknown, possibly unused; a very quiet sound.
	Sound ID 8E. Unused; another rev-up sound. Sonic Origins uses this sound for the wheel switches in Marble Garden Zone.
	Sound ID 8F. The sound the door on the pyramid in Sandopolis Zone makes when it opens, and the doors in Lava Reef Zone.
	Sound ID 90. Door closing sound from Sandopolis Zone, and also the sound of Knuckles hitting the ground after his defeat.
	Sound ID 92. The sound of a Hyudoro appearing.
	Sound ID 93. The sound that plays when the armour on the Egg Golem comes back on.
	Sound ID 95. The sound of the giant hand appearing in the Heat Arms fight.
	Sound ID 96. The sound the giant spikeballs in Lava Reef Zone make when they roll around.
	Sound ID 97. The sound a Toxomister makes when it sprays its toxic gases.
	Sound ID 98. The sound of a falling stalactite in Lava Reef Zone.
	Sound ID 99. Unused; A small "tick" sound.
	Sound ID 9A. The sound of the pop-up springs from Sky Sanctuary Zone.
	Sound ID 9B. The sound of the Egg Golem taking a step forward.
	Sound ID 9C. The sound that plays when a Super Emerald awakens.
	Sound ID 9D. The sound of the missile reticles in the Lava Reef Act 2 boss area.
	Sound ID 9E. The sound of a platform breaking upon coming into contact with the Hot Mobile.
	Sound ID A0. The sound of the Hot Mobile firing a missile.
	Sound ID A1. Unused; a low-humming, unsettling sound. This sound effect is later used by the Hotaru Hi-Watt mini-boss in Sonic Mania.
	Sound ID A2. The sound of the speed launchers in Flying Battery Zone and Death Egg Zone.
	Sound ID A3. The sound for Death Egg Zone's swinging platforms.
	Sound ID A4. The sound that Mecha Sonic makes when he goes super.
	Sound ID A5. Unused; sounds like something rising or powering up?
	Sound ID A6. Unused; another dashing noise.
	Sound ID AE. The sound used by the seesaw mushroom in Mushroom Hill Zone, and also in the Bonus Stages.
	Sound ID B5. A leftover from Sonic 1 that was used for the breakable diamonds in the Special Stage.
	Sound ID BC. Unused? Possible waterfall sound effect.
	Sound ID C2. The sound of the flamethrowers in Flying Battery Zone and Lava Reef Zone.
	Sound ID C4. The sound Red Eye makes when it gets angry.
	Sound ID C5. Unused; sounds like it would be used in coordination with sound C4. Sonic Origins uses this sound when Red Eye stops firing its laser.
	Sound ID CA. The sound of the light beam transportation systems in Death Egg Zone.
	Sound ID CE. The gusts of wind from Mushroom Hill Zone. Also used in Knuckles' ending after Super Mecha Sonic explodes.
	Sound ID CF. A louder version of CE that might be unused even in Sonic 3 & Knuckles.
	Sound ID D1. Possibly unused; another very faint sound that may sound like static.
	Sound ID D3. The sound used by the Death Egg as it flies through Sky Sanctuary Zone.
	Sound ID D4. Used by the bouncing puzzle room in Death Egg Zone.
	Sound ID D5. Used when the lava falls from Lava Reef Zone. Repeatedly pressing the button when playing this sound in the Sound Test makes it play longer.
	Sound ID D6. Unknown/unused; rumbling/electric sound?
	Sound ID D7. The sound of the elevators in Lava Reef Zone and Death Egg Zone.
	Sound ID D8. Unused; sounds like a screeching warning siren. Repeatedly pressing the button when playing this sound in the Sound Test makes it play longer.
	Sound ID D9. The sound the electromagnets in Flying Battery Zone and the black gravity spheres in Death Egg Zone make.
	Sound ID DA. The sound of the wind trap Knuckles activates in Mushroom Hill Zone.
	Sound ID DC-DF. All of these sounds are duplicates of DB (heard when running across water in Hydrocity Zone) and are likely placeholders. Sonic & Knuckles replaces DC with its credits medley.

Palettes

Palette	Description
	The palettes for Sonic 2's Sega screen, found at offset 08C134.
	Sonic and Tails' palette for Sonic 2's title screen, found at offset 08C1B4.
	For some reason, the palettes from the level select screen of the Sonic 2 prototypes can be found at offset 08C1D4.
	An underwater palette that might have been part of the palette used for the removed water in Launch Base Zone Act 1, found at offset 08CB14. Does not include colours for Sonic and Tails underwater.
	An early palette for the Glowing Spheres Bonus Stage, found at offset 08CDB4. It is exactly the same as in the 1993-11-03 and Sonic 3C 0408 prototypes.
	An early palette for the Slot Machine Bonus Stage, found at offset 08CE14. It is exactly the same as in the 1993-11-03 prototype, and is quite different from the Sonic 3C and Sonic & Knuckles prototypes.
	The palette cycle for the lava in Lava Reef Zone, found at offset 002EFE. It can be seen in-game if Lava Reef is accessed in this game.
	The palette cycle for the glowing background in Lava Reef Zone, found at offset 002F7E. It can be seen in-game if Lava Reef is accessed in this game.
	Duplicates of palettes used in Angel Island Zone Act 2 and IceCap Zone Act 2 respectively, found at offsets 05275C and 05277C.
	Knuckles' player palette used in Sonic & Knuckles and Sonic 3 & Knuckles, found at offset 08C2F6.

Knuckles

Some data for Knuckles seems to be in the game still. Using Game Genie codes ASCA-AAHC + ASCA-BA9Y created by LocalH, the player can select Knuckles when starting a new game, using Knuckles' unused character select icon. They will still play as Sonic, but Knuckles' Continue icon and name graphic for results tallies will be used, and the goal signpost will stop on Knuckles. The player can create a save file while using the codes, and the unused values will save, therefore they can play as "Knuckles" without needing to use the codes again.

Patch code FFFA81:0001 will make some of the bosses use behaviours normally reserved for Knuckles: Fire Breath will shoot bombs, the Screw Mobile will not fly down towards the water when creating a twister, and a spiked pillar will appear when fighting the Tunnelbot. After defeating the Beam Rocket, the game will attempt to play Knuckles' bomb cutscene in a broken form: the bomb will be in a corrupted state, and nothing else happens after the cutscene finishes.

Patch code FFB038:0200 adds Knuckles' ability to break through certain barriers to access his exclusive routes, but will disable the Insta-Shield as Knuckles does not have the move. This doesn't work in IceCap Zone and will result in map boundary glitches.

Surfboard intro

An unused intro sequence that was originally used in the November 3rd prototype remains in the ROM, in which Sonic surfs onto Angel Island, rather than riding in on the Tornado and becoming Super Sonic. The object used for this intro can be spawned in Angel Island Zone Act 1 via debug mode, but doing so will corrupt Sonic's sprites as it shares its VRAM address with the Sonic object. The sprites are based on Sonic 2's style, rather than those of the final Sonic 3; also shown here are the sprites used when Sonic jumps off the board:

This savestate ^(info) (45 kB) will allow you to see the full sequence in action (thanks to Nemesis). Another way to see the full sequence is to use the following PAR codes created by Fred Bronze:

• 004DF0:0002 + 004DF2:0B0E will enable the intro sequence, but some of the graphics will be wrong as the necessary graphics are no longer in the PLC.
• 05B084:0002 + 05B086:0014 + 05B088:86E0 + 05B08A:A520 + 05B08C:0014 + 05B08E:81A0 + 05B090:7A20 + 05B092:0014 + 05B094:8978 + 05B096:B0A0 + 00477A:7000 will add the required graphics to PLC 0 and make the intro load it.
• Finally, 020D3A:0004 + 020D3C:48B0 will make the intro load the title card and HUD when it finishes.

Launch Base Zone Act 1 water levels

Launch Base Zone Act 1 has five spots that raise or lower the water level, suggesting that it may have had water in it like Act 2. To re-enable the water, use patch code FFF730:0100 and change the VDP 0x04 to 0x14. The water levels can be found in the ROM at address 0x5350:

• The first level exists at ROM address 0x51EE and is supposed to raise the water level to 0A80, but it doesn't work.
• The second level starts at coordinates 0000 to 0E00 and raises the water to 0B00.
• The third level starts at coordinates 0E00 to 2340 and raises the level to 0A00.
• The fourth level starts at coordinates 2340 to 2C00 and lowers the level to 0AC8.
• The fifth level disappears the water, starting at coordinates 0AC8 to FFFF.

Competition mode title cards

The title card object has definitions for Competition mode levels that are fully programmed, but hidden behind a flag which is disabled. The following codes can be used to re-enable the title cards:

• 02CA90:6030 - Enable 2P zone title cards
• 02CACA:FE10 - Pick title card by Current_zone
• 02CB42:004D - Set art_tile instead of render_flags
• 02CB44:000B - Set art_tile instead of render_flags

When enabled, VRAM conflicts with the level graphics will occur which causes the title cards to display incorrectly.

Leftover Sonic 2 menus

By setting the game's screen mode to $24, the Sonic 2 options menu can be accessed in Sonic 3. Either use the patch code FFF600:2400, or follow the instructions on SCHG How-to:Restore Sonic 2 Menus to Sonic 3. Sonic 2's level select code can be entered here, along with Sonic 3's otherwise pointless debug mode code.

The 2-player menu from Sonic 2 can also be found by setting the screen mode to $1C, or using the patch code FFF600:1C00. Not much can be done in this menu however, each Zone is X'ed out and it plays an error sound when pressing .

Scrolling credits

The game has a unused and unfinished scrolling credits routine. It can be activated by setting the RAM address FA87 to 02 during the credits screen. Just small and large versions of the letters B through F scroll before cutting to the TRY AGAIN/logo as it was not finished. A YouTube video of the scrolling ending credits can be seen here. Normally the credits scrolls through static pages of text.

True level order/Unused levels

The level select menu reveals what the level order may have looked like had Sonic 3 and Sonic & Knuckles not been split into two separate games. The Sonic 3 levels are arranged the same as they are played in the game, but Flying Battery Zone from Sonic & Knuckles can be seen listed in between Carnival Night Zone and IceCap Zone. Following Launch Base Zone two more Sonic & Knuckles levels can be found, Mushroom Hill (which goes by the name Mushroom Valley here), and Sandopolis.

In a commentary found in the Sonic Jam Official Guide book, it was revealed that the transition between Flying Battery Zone and IceCap Zone would have Sonic break off the ship's door and use it as a snowboard.

Also, when a level is highlighted, a level icon from Sonic 2 is shown, with the icons appearing in the Sonic 2 order e.g. Angel Island has the Emerald Hill icon, Hydrocity has the Chemical Plant icon, Marble Garden has the Aquatic Ruin icon. Even the special stage has the Sonic 2 Special Stage icon. It can also be noted that the second '2P VS' level has an icon which resembles the cut Hidden Palace Zone from Sonic 2. However, in the Sonic Jam version of the game only the sound test icon is used.

None of the Zones that would later appear in S&K can be selected normally, including the S&K Bonus Stage selections.

• 

  Flying Battery's level slot still contains data, including earlier versions of its bosses!

• 

  Mushroom Valley's level slot contains an early object layout for both Acts that differs significantly from the final version of Sonic & Knuckles.

• 

  Although not much remains of Sandopolis Zone, it still has a unique start location that differs from the final version of Sonic & Knuckles.

SEGA screen technical details

The following table explains how the frames work on the SEGA screen, describing when the level select cheat code can be entered, when can it not, what frames have input disabled or enabled, and other info.

Description	Frames in current section		Frames since startup
	60FPS	50FPS	60FPS	50FPS
Game startup
Input disabled	1 - 9	1 - 8	1 - 9	1 - 8
Input accepted, but ignored	10 - 30	9 - 29	10 - 30	9 - 29
Input disabled	31 - 36	30 - 34	31 - 36	30 - 34
Input enabled, but ignored	37 - 58	35 - 56	37 - 58	35 - 56
Input almost always disabled	59 - 237	57 - 235	59 - 237	57 - 235
Skipping with possible on	78 94 110 126 142 158 174 190 206 222	76 92 108 124 140 156 172 188 204 220	N/A	N/A
Dark(ening) SEGA screen
Input enabled, but ignored	1 - 10	1 - 10	238 - 247	236 - 245
Input disabled	11 - 21	11 - 20	248 - 258	246 - 255
Cheat code input can start now
Input enabled	1 - 23	1 - 23	259 - 281	256 - 278
Input disabled	24 - 25	24	282 - 283	279
Input enabled	26 - 28	25 - 27	284 - 286	280 - 282
Input disabled	29 - 39	28 - 36	287 - 297	283 - 291
Input enabled	40	37	298	292
Input disabled	41	38	299	293
Input enabled	42 - 44	39 - 41	300 - 302	294 - 296
Input disabled	45 - 51	42 - 47	303 - 309	297 - 302
Input enabled	52	48	310	303
Input disabled	53	49	311	304
Input enabled	54 - 56	50 - 52	312 - 314	305 - 307
Input disabled	57 - 62	53 - 57	315 - 320	308 - 312
Input enabled	63	58 - 61	321	313 - 316
Input disabled	64	62 - 66	322	317 - 321
Input enabled	65 - 67	67 - 71	323 - 325	322 - 326
Input disabled	68 - 73	N/A	326 - 331	N/A
Input enabled	74 - 78	N/A	332 - 336	N/A
Input disabled, code opportunity ended	79	72	337	327

That's the reason why this code is so hard to input: the player has a short time to do it, it starts a small bit after what most people think (it was initially thought that input started when the background was starting to darken, whereas one needs to wait 21 frames, a bit before Sonic starts moving). Additionally, there are several lag frames in which the input isn't accepted.

Extra info

• The RAM address that stores the code's progress is 00FFFFD5.
• The game is only ready to let the SEGA screen be skipped to the darkening part on frame 59 (57 @50FPS) (which, in practical terms means frame 78 (76 @50FPS), seeing as frames 59 - 77 (57 - 75 @50FPS) are lag frames). However, the button can actually be used on frame 58 (56 @50FPS), and the skip will work... but the title screen music will be disabled.

Cheat device codes

These are cheat codes that can only be used with game enhancer devices. Support for these codes is available in most emulators.

Game Genie

Official codes, Sonic 3 alone

Code	Effect	Reference
AWHA-CA92	Don't lose rings.
SCGT-DJYL	Rings worth 2.
SCGT-DNYL	Rings worth 3.
SCGT-DTYL	Rings worth 4.
SCGT-DYYL	Rings worth 5.
SCGT-D2YL	Rings worth 6.
SCGT-D6YL	Rings worth 7.
SCGT-DAYL	Rings worth 8.
KRGT-CAE0	75 Rings needed for a free guy.
GLGT-CAE0	50 Rings needed for a free guy.
D4GT-CAE0	30 Rings needed for a free guy.
CWGT-CAE0	20 Rings needed for a free guy.
BLGT-CAE0	10 Rings needed for a free guy.
HCGT-DJZY	Get 2 free guys for 100 rings instead of 1.
HCGT-DNZY	Get 3 free guys for 100 rings.
HCGT-DTZY	Get 4 free guys for 100 rings.
HCGT-DYZY	Get 5 free guys for 100 rings.
HCGT-D2ZY	Get 6 free guys for 100 rings.
HCGT-D6ZY	Get 7 free guys for 100 rings.
HCGT-DAZY	Get 8 free guys for 100 rings.
AC5A-CAHN	Super ring powerup worth 0.
A05A-CAHN	Super ring powerup worth 5 instead of 10.
B85A-CAHN	Super ring powerup worth 15.
CW5A-CAHN	Super ring powerup worth 20.
DG5A-CAHN	Super ring powerup worth 25.
D45A-CAHN	Super ring powerup worth 30.
GL5A-CAHN	Super ring powerup worth 50.
NW5A-CAHN	Super ring powerup worth 100 (1-Up every time).
AJZA-CA8N	Super Sonic doesn't lose rings.
AJ3A-CA7A	Infinite lives.
AG4T-AAH4	Start with 1 life.
AL4T-AAH4	Start with 2 lives.
A04T-AAH4	Start with 5 lives.
BL4T-AAH4	Start with 10 lives.
DG4T-AAH4	Start with 25 lives.
GL4T-AAH4	Start with 50 lives.
NR4T-AAH4	Start with 99 lives.
ACAT-CAB6	Shield can be activated multiple times.
AJRT-CA8R	Invincibility power-ups last forever.
986A-CAB6	Invincibility lasts almost twice as long.
KR6A-CAB6	Invincibility lasts half as long.
E06A-CAB6	Invincibility lasts 1/4 as long.
SCFT-BJT4	Only need 6 chaos emeralds.
SCFT-BNT4	Only need 4 chaos emeralds.
SCFT-BTT4	Only need 3 chaos emeralds.
SCFT-B2T4	Only need 2 chaos emeralds.
ACGA-AA8T	1 Blue sphere needed for chaos emerald.
TAYA-CRB6	Bonus jump.
AAYA-CWB6	Super jump.
AAYA-C0B6	Mega-jump.
ATST-CA38	Sonic never drowns.
AA6T-AAXC	Level select menu enabled.
SCGA-BL0N + A4GA-A28T	Blue spheres worth 2.
SCGA-BR0N + A4GA-A28T	Blue spheres worth 3.
SCGA-BW0N + A4GA-A28T	Blue spheres worth 4.
SCGA-B00N + A4GA-A28T	Blue spheres worth 5.
SCGA-B40N + A4GA-A28T	Blue spheres worth 6.
SCGA-B80N + A4GA-A28T	Blue spheres worth 7.
SCGA-BC0N + A4GA-A28T	Blue spheres worth 8.

Unofficial codes, Sonic 3 alone

Code	Effect
AABT-AN3W	Bypass region lock.
ATLA-CARA	Invincibility.
AAYT-CAGC	Sonic can use bubble bounce (can’t use a Aqua Shield or become Super Sonic).
AAYT-CAY4	Sonic can use Electric Jump (can’t use Lighting shield or become Super Sonic).
AAYT-CAWT	Sonic can Use Fireball Attack (can’t use Fire Shield or become Super Sonic).
P42S-8ABL	All Powerful (Invincible, Aqua Breathe, Magnetism).
AAYT-CAHR	Become Super Sonic With 0 Emeralds.
AAYT-CAH0	Become Super Sonic With 0 Rings.
D3AT-AR2E	'Sound Test' Menu Enabled.
AAZA-CAEY	Don't Use Up Rings To Maintain The Super Sonic Transformation.
AE5A-AABL	Enable Debug (If using an emulator, "reset" the game after entering the code).
AFLA-CARE	Tails Always Swims.
VPLA-CACG	Tails Never Get Tired of Flying.
ASCA-AAHC + ASCA-BA9Y	Play as Knuckles (Knuckles appears at the save screen but you will control Sonic).

Action Replay

Unofficial codes, Sonic 3 alone

Code	Effect
008630:603C	Red Spheres have no effect in special stages (you can walk through them).
008672:6622 + 00868C:4E75	White and Red Star Spheres have no effect in special stages (they won't bump you backwards).
FFFE12:0009	Infinite Lives.
FFFE20:00C8	Infinite Rings.
FFF710:00	Rings Multiplier.
FFFE24:000F	Stop Timer.
FFE438:0001	Only Need 1 Blue Sphere For Chaos Emerald.
FFFFB0:0007	All Emeralds Collected.
FFB02A:006E	All Powerful (Invincible, Aqua Breathe, Magnetism).
FFB02B:XX	The value in XX is based on binary, with the following values going to each (unknown values are omitted): 00:None 01:Some projectiles blocked and rings not lost when you get hit 02:Invulnerability, disables ALL double jump attacks 10:Fire Shield 20:Lightning Shield 40:Water Shield 80:No change in movement or direction allowed while on ground Add together these hex values for the shield you want Example: 2(Invuln)+10(Fire Shield)+20(Lightning Shield)+40(Water Shield)=72 Having just a shield will not protect you from losing rings.
FFB02F:00	Never use up shield (Sonic)
FFFFFA:0100	Enable Debug Mode.
FFFFD0:0100	Enable Stage Select.
FFFE10:XXYY	Stage/Act Modifier. 00 - Angel Island 01 - Hydrocity 02 - Marble Garden 03 - Canival Night 04 - Flying Battery (incomplete) 05 - Icecap 06 - Launch Base 07 - Mushroom Valley (incomplete) 08 - Sandopolis (incomplete) 09 - Lost level 09 0A - Sky Sanctuary [?] 0B - Death Egg [?] 0C - The Doomsday [?] (incomplete) 0D - Lost level 0D 13 - Gumball Machine - Bonus Stage 14 - Glowing Spheres - Bonus Stage (incomplete) 15 - Slot Machine - Bonus Stage (incomplete) 16 - Act 1 = Lava Reef boss. Act 2 = Hidden Palace (vastly incomplete) 17 - Act 1 = Death Egg boss. Act 2 = other Hidden Palace (vastly incomplete) Garbled in 1P, normal in 2P OE - Azure Lake OF - Balloon Park 10 - Desert Palace 11 - Chrome Gadget 12 - Endless Mine
FFF711:??
FFFF95:00	Special Ring Always Available.