Sonic 3 & Knuckles

Sonic 3 & Knuckles
Developer: Sega Technical Institute Publisher: Sega Platform: Genesis Released in JP: October 28, 1994 Released in US: October 18, 1994 Released in EU: October 18, 1994 Released in AU: November 19, 1994 Released in KR: October 18, 1994 This game has unused areas. This game has unused code. This game has unused objects. This game has unused graphics. This game has unused music. This game has unused sounds. This game has debugging material. This game has a hidden sound test. This game has a hidden level select. This game has a bugs page

To do: Document version differences in Sonic Jam, the Sonic & Knuckles Collection, and other compilations.

Sonic 3 & Knuckles is a game that results when Sonic the Hedgehog 3 is inserted into Sonic & Knuckles by way of the "Lock-On" feature, thus creating a full 32 megabit game with an awkward title.

Sub-Page

Bugs

Level Select/Debug Mode

Sonic 3 & Knuckles' level select is performed similarly to that of Sonic & Knuckles: grab one of the rope swings in Angel Island Zone and press Left, Left, Left, Right, Right, Right, Up, Up, Up (or use the Pro Action Replay (PAR) code FFFFE0:0101). After the ring sound plays, press Start then A to return to the title screen.

At the title screen, "Sound Test" will be available below "Competition". This will open up the level select menu (with a sound test at the bottom-right). Press C on this menu to change your character (00 is Sonic & Tails, 01 is Sonic, 02 is Tails, and 03 is Knuckles).

When this code is enabled, you can perform three actions while the game is paused:

• Press A to go back to the title screen.
• Hold B to progress the game in slow motion.
• Press C to advance one frame.

Notes about the levels:

• Lava Reef Act 3 goes to the boss room. Debug mode is required to select this level as Knuckles.
• Lava Reef Act 4 goes to Hidden Palace Zone. Each character goes to their respective entrance in the level.
• Sky Sanctuary Act 1 is Sonic and Tails' version of the level and Act 2 is Knuckles'. Sonic and Tails cannot go to Knuckles' level and vice-versa.
• Knuckles can enter Death Egg, but he cannot defeat the Act 1 boss (he cannot jump high enough to hit the boss in the first phase).
• The Doomsday Act 2 leads to the final boss of Death Egg. If Knuckles defeats the boss, the game will reset to the SEGA screen.
• Knuckles cannot enter either Act of The Doomsday without debug mode enabled. Tails can enter Act 2, but not Act 1.
• If Sonic or Tails beats The Doomsday Zone, the bad ending will play if he doesn't have all the Chaos Emeralds and/or Super Emeralds.
• If Knuckles beats The Doomsday Zone, the game will reset to the SEGA screen.
• Bonus 1 goes to the Glowing Spheres game. Bonus 2 goes to the Slot Machine game. Finishing each stage will restart it.

Debug Mode

To unlock Debug Mode, enter Mushroom Hill Zone and grab one of the lifts, then press Left, Left, Left, Right, Right, Right, Up, Up, Up. A ring sound will play as a confirmation. Alternatively, use the Pro Action Replay code FFFFE2:0101. Afterward, to turn it on, go into the level select, and hold A while selecting a level.

Normal gameplay now has added debug features:

• Press A to reverse gravity (reaching the top of the level will kill you as if you fell off a bottomless cliff).
• Press B to enter edit mode.
• Press B + C to rapidly cycle through all available animation frames for the current character (pause the game and use frame advance to view individual frames). Press B again to return to normal gameplay.

In edit mode:

• The coordinates of the current object are shown by the top line of hex digits in the HUD.
• The coordinates of the current viewport are shown by the bottom line of hex digits in the HUD.
• Press A to cycle forwards through the object list.
• Press A + C to cycle backwards through the object list.
• Press B to enter normal mode.
• Press C to place the current object shown.

You can use debug mode to enter any level a character would normally not be able to enter (see above), though in some cases this causes player sprites to become corrupted.

Entering edit mode during some parts of the game (such as the light tubes in Death Egg) will crash the game. Entering edit mode and placing an object when dying may also crash the game.

Unused Palette

Directly after the regular palette script for the S&K special stage rings is an alternate, unused palette cycle.

It seems the developers originally played around with having the ring simply glow like Super Sonic, rather than the Hyper Sonic-esque rainbow strobe effect seen in the final version.

Unused Special Stages

Two unused Special Stages from both Sonic 3 and Sonic & Knuckles can be accessed via a hidden cheat code. First enter the level select and Debug Mode cheats and then set the Sound Test selection to 07, then press A + Start while selecting "Special Stage 1" to access the eighth Special Stage from Sonic 3, or "Special Stage 2" to access the eighth Special Stage from Sonic & Knuckles.

Completing these Special Stages will award you with an eighth Chaos/Super Emerald that is colored yellow (whereas the emerald was grey in Sonic 3). However, the emeralds you get from these Special Stages have no special effect in-game and will not appear on the results tally or in Hidden Palace.

It is worth noting that the eighth Special Stage from Sonic 3 has a different palette in this game compared to the one used in Sonic 3.

Interestingly enough, these zones returned in Sonic Mania as Bonus Stages, and Sonic 3's 8th Special Stage has some Blue Spheres replaced with rings, making it possible to get a perfect bonus.

Sonic 3 8th Special Stage	Sonic & Knuckles 8th Special Stage

Unused Objects

Graphic	Description
	A button of unknown purpose. It can be placed in either Act of Carnival Night Zone via debug mode, but it doesn't seem to do anything. This remains unused from Sonic 3 alone.
	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. This also remains unused from Sonic 3 alone.
	Some strange platform that isn't placed in any level, but the graphics fit perfectly with Launch Base Zone. It has no movement on its own when placed, and needs specific Pro Action Replay (PAR) codes to do so. To enable it, use the Pro Action Replay (PAR) code 1EFC52:1200 and it will replace the first ring monitor in Act 1. From there, enter FFF7E0:00FF to make it move down, and FFF7E0:0000 to make it return to its original position. (Source: Sonic Retro, shobiz)

Unused Audio

Music

These songs can be heard in the Level Select/Sound Test.

Sound ID	Song	Comments
$26		The Sonic 3 credits theme. Of the Sonic 3 tracks which were "replaced" in-game by their Sonic & Knuckles counterparts, only this song is still present. (Source: Sonic Retro)
$32		A short "Game Clear" jingle. Though Sonic 3 used this sound ID for its own jingle played after defeating the final boss, it isn't used in the Genesis version of Sonic 3 & Knuckles at all. This jingle did end up becoming used in the Sonic Origins version of this game when defeating Big Arm. A longer version of this jingle can be heard at the end of the credits medley.

Sound Effects

Even when locked on with Sonic 3, some sounds still go unused.

Sound ID	Sound	Comments
$3A		This is a shield sound leftover from Sonic the Hedgehog 2.
$40		Sounds like an electric zap. This sound would later be used for the Thunder Shield in Sonic Generations and Sonic Lost World.
$5A		Sounds like something revving up. This sound effect would see use in Sonic 3D Blast.
$6B		A slightly higher-pitched version of the sound used in Sonic 1 when touching some of the blocks in a Special Stage.
$6D		Sounds like a door closing.
$71		Duplicate of $3A; another shield sound leftover from Sonic the Hedgehog 2.
$7D		Sounds like mild rattling.
$84		Sounds like something charging up. Only seems to be referenced in some zone with a high level ID which is composed of garbage data.
$85		Sounds like it would have been used in cooperation with $84.
$8D		A very quiet sound.
$8E		Another electric rev-up sound. This sound effect was eventually used in Sonic Origins for the spindash-activated flywheels in Marble Garden Zone.
$99		A small "tick" sound.
$A1		A low-humming, unsettling sound.
$A5		Sounds like something rising or powering up?
$A6		Another dashing noise.
$B5		A leftover from Sonic 1 that was used for the breakable diamonds in the Special Stage. Might have been used for the Slot Machine Bonus Stage which is based off that Special Stage.
$BC		Possible unused waterfall sound effect?
$C5		Sounds like it would be used in coordination with $C4, the sound Red Eye makes when it's angry. This sound was used in Sonic Origins for when Red Eye calms down.
$D1		Another very faint sound that may sound like static.
$D6		Rumbling/electric sound?
$D8		Sounds like a screeching warning siren. Repeatedly pressing the C button when playing this sound in the Sound Test makes it play longer.
$DD - $DF		All of these sounds are duplicates of $DB (heard when running across water in Hydrocity Zone) and are likely placeholders.

DAC samples

To do: Replace disassembly names with accurate descriptions of what the samples are.

Plenty of DAC samples also go unused.

DAC ID	Sound	Comments
$89		Named in the disassembly as "dRideCymbal"
$96		Named in the disassembly as "dLooseSnare"
$9A		Named in the disassembly as "dMidTimpaniS3"
$A6		Named in the disassembly as "dDanceSnare"
$A7		Named in the disassembly as "dLooseKick"
		A completely unreferenced DAC sample, placed between samples $AF and $B1 in ROM.
$B8		Named in the disassembly as "dHipHopHitKick2"
$BD		Named in the disassembly as "dPowerKick2"

Sprite Oddities and Misalignments

Multiple sprites within Sonic 3 & Knuckles contain oddities or slightly misaligned mappings.

Oddities

Sonic

Sonic's sprites seem to be the most inconsistent, as many sprites use different, earlier versions of Sonic's head, including a straight edit of Sonic 2's sprite.

Sonic's sprites for running on a vertical corkscrew are the same as the corkscrew running sprite in Sonic 2 but flipped vertically. Oddly enough, they seem to have taken the time to redraw the first three frames of the animation yet left the rest of them untouched. This is strange due to the fact that the sprites for a horizontal corkscrew have been redrawn completely.

This oddity is a leftover from Sonic the Hedgehog 3, which in turn is leftover from the prototype. Strangely, this was not fixed in any version, not even in Sonic Origins.

Tails

Tails' sprites are, for the most part, ripped straight from Sonic the Hedgehog 2. However, not counting new sprites, a few have been redrawn.

Misaligned Mappings

Misaligned mappings appear prominently within Super Sonic's sprites.

Used Sprite	Intended Mapping	Comments
		On the 4th and 5th frames of the transform animation, the top half of the torso is erroneously shifted 2 pixels to the left.
		On the 3rd frame of the balance animation, the top of the head is erroneously shifted 2 pixels to the right.
		On all frames of the idle animation, the middle of the head is erroneously shifted 1 pixel to the left.