Sonic the Hedgehog 2 (16-bit)/Hidden content

Back to: Sonic the Hedgehog 2 (16-bit).

Level select

Play songs 19, 65, 09, 17 on the options screen, then hold + on title screen.

Edit mode

From the level select menu, play songs 01, 09, 09, 02, 01, 01, 02, 04 (1992-11-24 - the worldwide launch date of Sonic 2). A Ring sound should trigger. Select a Zone and hold until the title card disappears.

Edit mode does not work when playing as Tails in this game, even though the counters for debug mode are still intact here.

Night mode

After enabling edit mode, select a level on the level select screen and hold + until the title card disappears.

Get all Chaos Emeralds

From the level select menu, play songs 04, 01, 02, 06 on the sound test and a Chaos Emerald sound effect will trigger. This immediately gives the player all seven Chaos Emeralds, enabling Super Sonic.

Swap Tails for Miles

Press at the title screen. This will cause all instances of "Tails" to change to "Miles", except in the Japanese version where the reverse will happen. This also toggles the trademark symbols on the Sega logo and the title screen.

14 continues

Play songs 01, 01, 02, 04 on the options screen. An incorrect sound command is issued, causing Oil Ocean Zone music to continue playing until a reset.

Unused content

Art

Tiles

Art	Description
23 27 129 141 147 178 179 200 201 208 209 219 220 243 244 276 284 285 286 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 308 313 314 319 321 324 326 327 343 347 386 387 388 391 393 394 398 427 527 528 534 535 536 592 606 610 611 624 626 638 650 651 659	The old ball launcher among other graphics in Oil Ocean Zone. Tile IDs: 017, 01B, 081, 08D, 093, 0B2, 0B3, 0C8, 0C9, 0D0, 0D1, 0DB, 0DC, 0F3, 0F4, 114, 11C, 11D, 11E, 123, 124, 125, 126, 127, 128, 129, 12A, 12B, 12C, 12D, 12E, 12F, 130, 131, 134, 139, 13A, 13F, 141, 144, 146, 147, 157, 15B, 182, 183, 184, 187, 189, 18A, 18E, 1AB, 20F, 210, 216, 217, 218, 250, 25E, 262, 263, 270, 272, 27E, 28A, 28B, 293.
35 36 37 38 40 41 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 100 101 102 103 104 159 194 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 327 372 379 406 407 408 409 410 411 412 413 414 417 418 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 484 486 487 488	Remnants of the diagonal platforms and some unused grey pipes in Metropolis Zone. Tile IDs: 023, 024, 025, 026, 028, 029, 048, 049, 04A, 04B, 04C, 04D, 04E, 04F, 050, 051, 052, 053, 054, 055, 056, 057, 058, 059, 05A, 05B, 05C, 05D, 05E, 05F, 060, 061, 062, 064, 065, 066, 067, 068, 09F, 0C2, 134, 135, 136, 137, 138, 139, 13A, 13B, 13C, 13D, 13E, 13F, 140, 141, 142, 143, 144, 145, 147, 174, 17B, 196, 197, 198, 199, 19A, 19B, 19C, 19D, 19E, 1A1, 1A2, 1AF, 1B0, 1B1, 1B2, 1B3, 1B4, 1B5, 1B6, 1B7, 1B8, 1B9, 1BA, 1BB, 1BC, 1BD, 1BE, 1BF, 1C0, 1C1, 1C2, 1C3, 1C4, 1C5, 1E4, 1E6, 1E7, 1E8.
601 610 616 636	Some unused clouds in Sky Chase Zone. Tile IDs: 259, 262, 268, 27C
327 333 337 343 354 364 443 504 510 511 513 528 529 533 537 538 551 552 672 674 695 739	Wing Fortress Zone tiles, possibly also desgined for Sky Chase Zone. Tile IDs: 147, 14D, 151, 157, 162, 16C, 1BB, 1F8, 1FE, 1FF, 201, 210, 211, 215, 219, 21A, 227, 228, 2A0, 2A2, 2B7, 2E3.

Sprites

Art	Description
	An animation very similar to one used in Wing Fortress Zone when Sonic grabs the panels on the side of the ship. However, this is vertical. Its frame IDs are 52 and 53.
	An alternate death frame for Sonic, defined in animation 16 with a frame ID of 5E. This returns from (and is also unused in) Sonic the Hedgehog.
	Unused decorative objects for Chemical Plant Zone, stored at 0x0383-0x0393 in VRAM. These can be placed in the iOS/Android 2013 version's debug mode.
	An animation for Water Eggman which shows Dr. Eggman dropping chemicals on himself. This animation has been around since the Nick Arcade prototype, but it was never implemented. A fix to implement the lost animation can be found here.
	A holder for Oil Ocean Zone's ball and spring object (see below). This appeared in the Simon Wai prototype, and is still loaded into VRAM in the final game.
	An unused animation for Aquis spitting up oil, along with an oil spray.
	Unused frame of the Balkiry badnik with landing gear. It's possible that they were originally intended to take off from the Wing Fortress Zone as it passed by. If a Balkiry is selected in debug mode, this sprite will be seen instead of its flying one.
	Walking sprites of Tocky, who pops out of the Badniks in Sky Chase Zone. Normally the player will never see this, since the animal never has the opportunity to hit the ground. In order to see it, the player must use debug mode to create and destroy a Badnik while the Wing Fortress passes by. This animation would later make an appearance in Sonic Mania, as Tocky can be found in Titanic Monarch Zone.
	Picky, a returning animal from the original Sonic the Hedgehog, is present in Death Egg Zone. However, there are no Badniks or animal capsules, so he's never seen.
	In Death Egg Zone, getting hit with one or more Rings during the Mecha Sonic battle causes Eggman to laugh. However, this is never actually seen outside of debug mode because the Zone has no Rings. In the 2013 mobile remake, this animation can be seen normally if the player dies during the fight. In 3D Sonic the Hedgehog 2 it can also be seen if the player is hurt by Mecha Sonic if the Ring Keeper mode is on.
	Level Select icon for Hidden Palace Zone, which never made it into the final game. The art however, is present in Sonic 3's level select. Pro Action Replay code 0096D8:0303 will cause it to replace the Emerald Hill Zone icon in the Stage Select.

Objects

Placeable in edit mode

Art	Description
	Unused door barriers for Aquatic Ruin Zone, which function like the door barriers found in other Zones.
	A strange platform made of Rings in Mystic Cave Zone. When placed, this object will slowly swing in an anti-clockwise direction and can be stood on. This object has existed since the Simon Wai prototype, and its object ID is $73.
	A ball and spring object, which can be placed in Oil Ocean Zone. If a button is placed near it and pressed, the ball will pop out and start rolling in whichever direction Sonic was facing when the object was placed. It does not collide with objects (such as breakable floors or elevators), and it will go up slopes and even vertical walls without slowing or stopping. It is used in the Simon Wai and alpha prototypes. Its object ID is $46.
	A horizontal version of the breakable pressure stopper in Oil Ocean Zone. These can be jumped on, but they will send Sonic and Tails left or right rather than up. Once Sonic is travelling, the player can't make him stop unless he collides with an object - even in edit mode the player will continue to travel. This would have been used in the Simon Wai layout of the Zone, but has no purpose in the final layout.
	Large laser shooting through a spinning platform in Wing Fortress Zone. If the sub-ID of the spinning platforms has bit 02 of their subtype set but not 04, they will become this object. Its object ID is $B7.
	Weird spinning pole in Wing Fortress Zone that acts like a Badnik - the player can destroy it, and it can hurt them, but it doesn't actually move. Its object ID is $BF.

Others

Art	Description
	A static or blank monitor which harms the player when broken. Never seen in-game. To see it, a monitor's subtype should be set to 00.
	A hovering platform for Chemical Plant Zone that has been around since the Nick Arcade prototype. Every 1024 frames, it will slowly rise up for 128 frames, float in the air, then come back down 128 frames later. The amount of time it floats in the air is 128*(lower four bits of subtype) frames. The upper four bits can be used to offset when it starts to rise in the air. Its object ID is $0C.
	The blue bubble snakes in Chemical Plant Zone have many subtypes that define their movement pattern (00-0F for jumping back and forth, 10-1F for jumping between the floor and ceiling) and their length, which can be any number of segments between 1 and 16. However, only those that are 6 segments long are used (subtypes 05 and 15), leaving all other subtypes unused.
	Although very similar to the small platforms used in Metropolis Zone, this platform behaves strangely, usually rising at an angle. Its object ID is $6C.
	The emerald-shaped object that was used in Hidden Palace Zone to block off a tube. The graphics are long gone, but the code is still there. It's a simple solid indestructible object and its coding hasn't changed since the Nick Arcade prototype. Its object ID is $12.
	The waterfall object from Hidden Palace Zone, which is also left over. Again, the graphics no longer exist in the ROM. Its height is equal to 16*(lower five bits of subtype)+16 pixels. Placing one with a subtype greater than 17 will spawn garbage objects on the right. Its object ID is $13.
	The spinning log spikes from Sonic the Hedgehog's Green Hill Zone. Unfortunately, the graphics have been deleted, but the coding is intact. Its object ID is $17.

Score tally

This configuration of the score tally is unused but was meant for Zones with a single Act (Sky Chase Zone, etc). It can be made to appear by using debug mode and placing, then breaking a capsule.

Level chunks

Emerald Hill Zone

[[File:

1

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01

[[File:

5

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05

[[File:

14

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0E

[[File:

21

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15

[[File:

23

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17

[[File:

50

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32

[[File:

86

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56

[[File:

122

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7A

[[File:

127

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7F

[[File:

166

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A6

[[File:

174

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AE

[[File:

210

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D2

[[File:

216

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D8

[[File:

217

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D9

[[File:

218

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DA

[[File:

220

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DC

[[File:

231

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E7

[[File:

237

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ED

Chemical Plant Zone

[[File:

29

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1D

[[File:

74

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4A

[[File:

137

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89

Casino Night Zone

[[File:

34

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22

[[File:

48

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30

[[File:

68

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44

[[File:

72

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48

[[File:

73

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49

[[File:

80

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50

[[File:

83

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53

[[File:

84

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54

[[File:

87

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57

[[File:

90

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5A

[[File:

109

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6D

[[File:

111

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6F

[[File:

112

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70

[[File:

114

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72

[[File:

119

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77

[[File:

124

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7C

[[File:

234

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EA

Hill Top Zone

[[File:

166

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A6

[[File:

174

|120x120px|]]

AE

[[File:

210

|120x120px|]]

D2

[[File:

216

|120x120px|]]

D8

[[File:

217

|120x120px|]]

D9

[[File:

218

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DA

[[File:

220

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DC

[[File:

231

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E7

[[File:

237

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ED

[[File:

245

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F5

Mystic Cave Zone

[[File:

30

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1E

[[File:

58

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3A

[[File:

79

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4F

[[File:

136

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88

[[File:

202

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CA

[[File:

205

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CD

[[File:

206

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CE

[[File:

207

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CF

[[File:

208

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D0

[[File:

209

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D1

[[File:

215

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D7

[[File:

230

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E6

Oil Ocean Zone

None of the chunks listed here are referenced in the table that the game checks to determine whether or not Sonic & Tails should slide.

[[File:

9

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09

[[File:

43

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2B

[[File:

44

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2C

[[File:

89

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59

[[File:

94

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5E

[[File:

98

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62

[[File:

109

|120x120px|]]

6D

[[File:

115

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73

[[File:

118

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76

[[File:

121

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79

[[File:

129

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81

[[File:

132

|120x120px|]]

84

[[File:

134

|120x120px|]]

86

[[File:

138

|120x120px|]]

8A

[[File:

148

|120x120px|]]

94

[[File:

151

|120x120px|]]

97

[[File:

158

|120x120px|]]

9E

[[File:

160

|120x120px|]]

A0

[[File:

165

|120x120px|]]

A5

[[File:

166

|120x120px|]]

A6

[[File:

169

|120x120px|]]

A9

[[File:

170

|120x120px|]]

AA

[[File:

178

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B2

[[File:

188

|120x120px|]]

BC

[[File:

204

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CC

[[File:

208

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D0

[[File:

210

|120x120px|]]

D2

[[File:

211

|120x120px|]]

D3

[[File:

214

|120x120px|]]

D6

[[File:

219

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DB

[[File:

220

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DC

[[File:

222

|120x120px|]]

DE

[[File:

224

|120x120px|]]

E0

[[File:

233

|120x120px|]]

E9

[[File:

234

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EA

[[File:

240

|120x120px|]]

F0

[[File:

245

|120x120px|]]

F5

[[File:

246

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F6

[[File:

248

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F8

[[File:

249

|120x120px|]]

F9

[[File:

255

|120x120px|]]

FF

Metropolis Zone

[[File:

3

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03

[[File:

105

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69

[[File:

121

|120x120px|]]

79

[[File:

125

|120x120px|]]

7D

[[File:

138

|120x120px|]]

8A

[[File:

182

|120x120px|]]

B6

[[File:

208

|120x120px|]]

D0

[[File:

213

|120x120px|]]

D5

[[File:

220

|120x120px|]]

DC

Wing Fortress Zone

[[File:

67

|120x120px|]]

43

[[File:

72

|120x120px|]]

48

[[File:

79

|120x120px|]]

4F

[[File:

87

|120x120px|]]

57

[[File:

98

|120x120px|]]

62

[[File:

152

|120x120px|]]

98

[[File:

221

|120x120px|]]

DD

Background data

Aquatic Ruin Zone

Code exists to scroll part of the top tree background layer at a different rate, giving the impression it is closer to the camera. As the code executes, the effect is reverted, so cannot be not seen without hacking. It is theorised that this may be a leftover from an early version of the level, as with the final art the seam is quite obvious.

Hill Top Zone

Hill Top Zone's background is partially optimised for 2-player mode; the background scrolls independently for both players, which cannot be said for other 1-player only levels. However, the parallax effect for the clouds is missing and some parts are corrupted, and while sharing data with Emerald Hill Zone means the foreground also renders correctly, objects are not optimised, meaning the experience is still noticeably buggy.

The final version of Hill Top Zone is also not suited to 2-player thanks to some level gimmicks, such as its inside lava sections; these make it impossible to back-track to the beginning of the stage by creating dead-ends, so if the two players were at opposite ends, the slower player would in theory get stuck.

Oil Ocean Zone

Due to the way scrolling is handled in Oil Ocean Zone, part of the background is never seen.

Audio

Music

Audio	Description
	In the sound test, song $10 is a unused song. This has been established to be the music meant for Hidden Palace Zone.

Sound effects

Sounds not used anywhere in the game can be heard in the sound test, some of which are leftovers from the original Sonic the Hedgehog.

Audio	ID	Description
Sonic the Hedgehog leftovers
	29	The sound for touching the R, Up, and Down Special Stage blocks.
	31	Scrap Brain Zone electricity.
	3A	The sound for touching the colour-changing diamonds in the Special Stage.
	43	The sound for entering Giant Rings at the end of an Act.
	47	The chain pulling sound from Marble Zone.
	49	The bonus point tags found at the end of an Act.
Other sounds
	38	Sounds similar to the sound of spikes popping up. Also unused in Sonic 1.
	51	Unknown. Sounds like something popping or skidding on the ground.
	52	A low siren, similar to $53 which is used in the 2-Player mode.
	68	Sounds like a slightly shorter version of Mystic Cave Zone's bridges stopping in place ($69).

Level slots

Like its predecessor, Sonic 2 on the Mega Drive lays out its levels in a different order internally to how the player sees them when playing through the game. It gives some clues as to what the original progression looked like, and the differences are quite significant.

The internal level order can be seen by using Pro Action Replay code (FFFE10:??00), substituting the question marks with the hexadecimal values for the level slots described in the table below and then attempting to enter any level (any number past 10 crashes the game). Metropolis Zone covers two level slots as it has three Acts.

Level slot	Level name	In-game order	Comments
00	Emerald Hill Zone	01
01	Unknown		Plays Emerald Hill Zone's music.
02	Wood Zone	Scrapped	Palette is all that remains. Plays Metropolis Zone's music.
03	Unknown		Plays Oil Ocean Zone's music.
04	Metropolis Zone	08
05	Metropolis Zone (Act 3)	09
06	Wing Fortress Zone	11
07	Hill Top Zone	05
08	Hidden Palace Zone	Scrapped	Palette and object/ring locations remain. Plays unused track #10.
09	Unknown		Plays Sky Chase Zone's music.
100A	Oil Ocean Zone	07
110B	Mystic Cave Zone	06
120C	Casino Night Zone	04
130D	Chemical Plant Zone	02
140E	Death Egg Zone	12	Occupied by Genocide City Zone in prototypes.
150F	Aquatic Ruin Zone	03
1610	Sky Chase Zone	10

This order is mirrored (with empty slots cut out) by some prototype level select screens. All empty slots are fundamentally broken, loading varying amounts of graphics data from Emerald Hill Zone (depending on the build).

Three slots in the game remain empty in all versions of Sonic 2 (save for the very early Nick Arcade prototype which is using the Sonic 1 level order). There has been much speculation over the years about what these slots were reserved for (if anything) - possible candidates include Brenda Ross's "desert" and "winter" zones which were thought to be at least partially complete, or possibly Genocide City Zone before it was transformed into Metropolis Zone Act 3. The team are known to have explored many level ideas during development, most of which did not make it past the design stage.

Commentary found in the Sonic Jam strategy guide reveals that the level order could have been even more different. It states that Chemical Plant Zone was meant to be the 10th Zone back when the game was planned as an 18-Zone game.

Unused slots

In all cases, Acts 1 and 2 are identical. Metropolis "Act 4" loads a duplicate of Metropolis Act 3 (with a different starting position) while "Act 2" of Sky Chase, Wing Fortress and Death Egg load their Act 1 counterparts without objects.

• 

  01 (unknown)

• 

  02 (Wood Zone)

• 

  03 (unknown)

• 

  08 (Hidden Palace Zone)

• 

  09 (unknown)

Inaccessible Rings

There are some levels that have Rings in places that can't be reached normally. This makes getting a Perfect Bonus in these stages impossible.

Screenshot	Level	Approximate coordinates	Description
	Aquatic Ruin Zone Act 2	1FA90626	Two horizontally lined rings.
	Casino Night Zone Act 2	027F00F8	Two groups of seven rings. These are right at the start of the level but cannot be reached with a jump or using nearby objects.
	Mystic Cave Zone Act 2	16050156 1712016D	Three horizontally lined rings, and a nearby curve of rings, similar to ones found near swings. Both sets of rings are found in the ceiling.
	Oil Ocean Zone Act 2	1A0001F8 0B9F03B0 1245021C	Three horizontally lined rings, close to the launcher and invincibility monitor. Three vertically lined rings stuck in a block which prohibits access to them. Rings in a upside down v shape pattern. They are stuck inside the wall, thus unaccessable.
	Metropolis Zone Act 2	02C0043F	Three slanted rings, in the floor that has a ten-ring monitor and a cog close-by.

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. There are two versions of this game. If one code doesn't work on your game, then try the other.

Game Genie

Official codes (REV00)

Code	Effect	Reference
SATA-DJTJ	Rings worth 2 (player 1).
SATA-DNTJ	Rings worth 3 (player 1).
SATA-DTTJ	Rings worth 4 (player 1).
SATA-DYTJ	Rings worth 5 (player 1).
SATA-D2TJ	Rings worth 6 (player 1).
SATA-D6TJ	Rings worth 7 (player 1).
SATA-DATJ	Rings worth 8 (player 1).
AE8A-AADN	Start with 1 life instead of 3 (player 1).
AY8A-AADN	Start with 5 lives (player 1).
A68A-AADN	Start with 7 lives (player 1).
BE8A-AADN	Start with 9 lives (player 1).
DE8A-AADN	Start with 25 lives (player 1).
GJ8A-AADN	Start with 50 lives (player 1).
KN8A-AADN	Start with 75 lives (player 1).
NN8A-AADN	Start with 99 lives (player 1).
JW3A-CA4Y	Infinite lives (player 1).
SATA-DJW8	Rings worth 2 (player 2).
SATA-DNW8	Rings worth 3 (player 2).
SATA-DTW8	Rings worth 4 (player 2).
SATA-DYW8	Rings worth 5 (player 2).
SATA-D2W8	Rings worth 6 (player 2).
SATA-D6W8	Rings worth 7 (player 2).
SATA-DAW8	Rings worth 8 (player 2).
AE8A-AADW	Start with 1 life instead of 3 (player 2).
AY8A-AADW	Start with 5 lives (player 2).
A68A-AADW	Start with 7 lives (player 2).
BE8A-AADW	Start with 9 lives (player 2).
DE8A-AADW	Start with 25 lives (player 2).
GJ8A-AADW	Start with 50 lives (player 2).
KN8A-AADW	Start with 75 lives (player 2).
NN8A-AADW	Start with 99 lives (player 2).
JXGA-CA7W	Infinite lives (player 2).
KBVT-CAE2	Jump lower.
FVVT-CAE2	Jump a little higher.
EBVT-CAE2	Jump a lot higher (Switch off if you get stuck somewhere or want to go in the water).
CBVT-CAE2	Jump really high (Switch off if you get stuck somewhere or want to go in the water).
A02T-CAGL	Sonic stays invincible for a shorter time after getting hit.
982T-CAGL	Sonic stays invincible for a longer time after getting hit.
ALTA-CA82	Sonic becomes invisible and invincible for the rest of the level after getting hit.
ALTA-CA9Y	Once invincible [stars], Sonic stays Invincible for the rest of the level.
ATTT-CA58	Sonic doesn't lose rings when hit.
ATTT-CA6W	Tails doesn't lose rings when hit.
ATTT-CA6W	Only 1 ring needed instead of 50 to enter special stage.
SBJA-HJV2	Rings worth 2 in special stages (Sonic only/Doesn't show on screen).
SBJA-HNV2	Rings worth 3 in special stages (Sonic only/Doesn't show on screen).
SBJA-HTV2	Rings worth 4 in special stages (Sonic only/Doesn't show on screen).
SBJA-HYV2	Rings worth 5 in special stages (Sonic only/Doesn't show on screen).
SBJA-H2V2	Rings worth 6 in special stages (Sonic only/Doesn't show on screen).
SBJA-H6V2	Rings worth 7 in special stages (Sonic only/Doesn't show on screen).
SBJA-HAV2	Rings worth 8 in special stages (Sonic only/Doesn't show on screen).
SBJA-HJV8	Rings worth 2 in special stage (Tails only/Doesn't show on screen).
SBJA-HNV8	Rings worth 3 in special stages (Tails only/Doesn't show on screen).
SBJA-HTV8	Rings worth 4 in special stages (Tails only/Doesn't show on screen).
SBJA-HYV8	Rings worth 5 in special stages (Tails only/Doesn't show on screen).
SBJA-H2V8	Rings worth 6 in special stages (Tails only/Doesn't show on screen).
SBJA-H6V8	Rings worth 7 in special stages (Tails only/Doesn't show on screen).
SBJA-HAV8	Rings worth 8 in special stages (Tails only/Doesn't show on screen).
ACZT-CACN	Need 0 chaos emeralds to become Super Sonic (Don't grab more than needed).
AGZT-CACN	Need 1 Chaos Emerald to become Super Sonic (Don't grab more than needed).
ALZT-CACN	Need 2 chaos emeralds to become Super Sonic (Don't grab more than needed).
ARZT-CACN	Need 3 chaos emeralds to become Super Sonic (Don't grab more than needed).
AWZT-CACN	Need 4 chaos emeralds to become Super Sonic (Don't grab more than needed).
A0ZT-CACN	Need 5 chaos emeralds to become Super Sonic (Don't grab more than needed).
A4ZT-CACN	Need 6 chaos emeralds to become Super Sonic (Don't grab more than needed).
AGZT-CACY + K4ZT-CA92	Need 1 ring to become Super Sonic, don't lose rings with time.
A0ZT-CACY	Need 5 rings to become Super Sonic.
BLZT-CACY	Need 10 rings to become Super Sonic.
DGZT-CACY	Need 25 rings to become Super Sonic.
FCZT-CACY	Need 40 rings to become Super Sonic.
K4ZT-CA92	Super Sonic doesn't lose rings with time.
RE8A-A60G	Level select menu enabled.
2VAT-BCRA	Start most levels with some rings (1 player game only).

Official codes (REV01)

Code	Effect	Reference
SAST-DJ1A	Rings worth 2 (player 1).
SAST-DN1A	Rings worth 3 (player 1).
SAST-DT1A	Rings worth 4 (player 1).
SAST-DY1A	Rings worth 5 (player 1).
SAST-D21A	Rings worth 6 (player 1).
SAST-D61A	Rings worth 7 (player 1).
SAST-DA1A	Rings worth 8 (player 1).
AE8A-AAD2	Start with 1 life instead of 3 (player 1).
AY8A-AAD2	Start with 5 lives (player 1).
A68A-AAD2	Start with 7 lives (player 1).
BE8A-AAD2	Start with 9 lives (player 1).
DE8A-AAD2	Start with 25 lives (player 1).
GJ8A-AAD2	Start with 50 lives (player 1).
KN8A-AAD2	Start with 75 lives (player 1).
NN8A-AAD2	Start with 99 lives (player 1).
JW3A-CA4J	Infinite lives (player 1).
SATA-DJVW	Rings worth 2 (player 2).
SATA-DNVW	Rings worth 3 (player 2).
SATA-DTVW	Rings worth 4 (player 2).
SATA-DYVW	Rings worth 5 (player 2).
SATA-D2VW	Rings worth 6 (player 2).
SATA-D6VW	Rings worth 7 (player 2).
SATA-DAVW	Rings worth 8 (player 2).
AE8A-AAD8	Start with 1 life instead of 3 (player 2).
AY8A-AAD8	Start with 5 lives (player 2).
A68A-AAD8	Start with 7 lives (player 2).
BE8A-AAD8	Start with 9 lives (player 2).
DE8A-AAD8	Start with 25 lives (player 2).
GJ8A-AAD8	Start with 50 lives (player 2).
KN8A-AAD8	Start with 75 lives (player 2).
NN8A-AAD8	Start with 99 lives (player 2).
JXGA-CA7G	Infinite lives (player 2).
KBVT-CAE2	Jump lower.
FVVT-CAE2	Jump a little higher.
EBVT-CAE2	Jump a lot higher (Switch off if you get stuck somewhere or want to go in the water).
CBVT-CAE2	Jump really high (Switch off if you get stuck somewhere or want to go in the water).
A02T-CAF8	Sonic stays invincible for a shorter time after getting hit.
982T-CAF8	Sonic stays invincible for a longer time after getting hit.
ALTA-CA8N	Sonic becomes invisible and invincible for the rest of the level after getting hit.
ALTA-CA9J	Once invincible [stars], Sonic stays Invincible for the rest of the level.
ATTT-CA4W	Sonic doesn't lose rings when hit.
ATTT-CA5G	Tails doesn't lose rings when hit.
AH2T-CAH6	Only 1 ring needed instead of 50 to enter special stage.
SBJA-HJWJ	Rings worth 2 in special stages (Sonic only/Doesn't show on screen).
SBJA-HNWJ	Rings worth 3 in special stages (Sonic only/Doesn't show on screen).
SBJA-HTWJ	Rings worth 4 in special stages (Sonic only/Doesn't show on screen).
SBJA-HYWJ	Rings worth 5 in special stages (Sonic only/Doesn't show on screen).
SBJA-H2WJ	Rings worth 6 in special stages (Sonic only/Doesn't show on screen).
SBJA-H6WJ	Rings worth 7 in special stages (Sonic only/Doesn't show on screen).
SBJA-HAWJ	Rings worth 8 in special stages (Sonic only/Doesn't show on screen).
SBJA-HJWR	Rings worth 2 in special stage (Tails only/Doesn't show on screen).
SBJA-HNWR	Rings worth 3 in special stages (Tails only/Doesn't show on screen).
SBJA-HTWR	Rings worth 4 in special stages (Tails only/Doesn't show on screen).
SBJA-HYWR	Rings worth 5 in special stages (Tails only/Doesn't show on screen).
SBJA-H2WR	Rings worth 6 in special stages (Tails only/Doesn't show on screen).
SBJA-H6WR	Rings worth 7 in special stages (Tails only/Doesn't show on screen).
SBJA-HAWR	Rings worth 8 in special stages (Tails only/Doesn't show on screen).
ACZT-CACA	Need 0 chaos emeralds to become Super Sonic (Don't grab more than needed).
AGZT-CACA	Need 1 Chaos Emerald to become Super Sonic (Don't grab more than needed).
ALZT-CACA	Need 2 chaos emeralds to become Super Sonic (Don't grab more than needed).
ARZT-CACA	Need 3 chaos emeralds to become Super Sonic (Don't grab more than needed).
AWZT-CACA	Need 4 chaos emeralds to become Super Sonic (Don't grab more than needed).
A0ZT-CACA	Need 5 chaos emeralds to become Super Sonic (Don't grab more than needed).
A4ZT-CACA	Need 6 chaos emeralds to become Super Sonic (Don't grab more than needed).
AGZT-CACJ + K4ZT-CA9N	Need 1 ring to become Super Sonic, don't lose rings with time.
A0ZT-CACJ	Need 5 rings to become Super Sonic.
BLZT-CACJ	Need 10 rings to become Super Sonic.
DGZT-CACJ	Need 25 rings to become Super Sonic.
FCZT-CACJ	Need 40 rings to become Super Sonic.
K4ZT-CA9N	Super Sonic doesn't lose rings with time.
RE8A-A60W	Level select menu enabled.
2VAT-BCRN	Start most levels with some rings (1 player game only).
GJ8A-AA4G	Skip straight to the ending sequence.

Unofficial codes (REV00)

Code	Effect
ADFT-8AF6	Regular level music plays when turning into Super Sonic.
ACLA-ATDR	Access Hidden Palace Zone by selecting Death Egg on the Level Select menu (no solid floors, glitched graphics, etc).

Unofficial codes (REV01)

Code	Effect
ACZT-CACA	Become Super Sonic With 0 Emeralds.
ADFT-8AF6	Regular level music plays when turning into Super Sonic.
982T-C9F8	Keep flashing after hit/Invincible (If you have rings).
ACLA-ATD4	Access Hidden Palace Zone by selecting Death Egg on the Level Select menu (no solid floors, glitched graphics, etc).
ACLA-AECY	Access Wood Zone by selecting Emerald Hill Zone on the Stage Select screen. (Buggy, pallete-swapped Emerald Hill Zone).

Action Replay

Due to the fact that Pro Action Replay Effects RAM and that RAM is the same regardless of the game revision there is no need for version specific codes. These codes should work in all versions.

Unofficial codes

Code	Effect
FFFE12:0009	Infinite Lives.
FFFE20:00C8	Infinite Rings.
FFB030:00FF	Invincibility For Sonic (Enemies Can't Touch You/Can't collect Rings).
FFB06A:01	Invincibility For Tails (Always Have Shield).
FFB070:00FF	Invincibility For Tails (Enemies Can't Touch You).
FFB028:FA	Infinite Time Underwater For Sonic.
FFB068:FA	Infinite Time Underwater For Tails.
FFF761:6410	Sonic has Super Speed.
FFFEC1:6410	Tails has Super Speed.
FFFFB1:07	Enable Super Sonic (All Chaos Emeralds Collected).
FFB02B:01	Always have Shield.
FFFE19:01	Play As Super Sonic (No Powers).
FFF711:??	HUD Display Modifier (00: Off, 01: On).
FFFFFA:0100	Enable Debug Mode.
FFFFD0:0100	Enable Stage Select (+ on Title Screen).
FFFE10:XXYY	Stage/Act Modifier (XX: Zone, YY: Level). 00 - Emerald Hill 04 - Metropolis 05 - Metropolis 3 06 - Wing Fortress 07 - Hill Top 08 - Hidden Palace (!) 0A - Oil Ocean 0B - Mystic Cave 0C - Casino Night 0D - Chemical Plant 0E - Death Egg 0F - Aquatic Ruin 10 - Sky Chase
FFB461:01	Defeat Final Stage Bosses With 1 Hit.
FFB521:01	Defeat Stage 1 Robotnik With 1 Hit.
FFB621:01	Defeat Stage 2 Robotnik With 1 Hit.
FFB721:01	Defeat Stage 3 Robotnik With 1 Hit.
FFB821:01	Defeat Stage 4 Robotnik With 1 Hit.
FFB921:01	Defeat Stage 5 Robotnik With 1 Hit.
FFBA21:01	Defeat Stage 6 Robotnik With 1 Hit.
FFBB21:01	Defeat Stage 7 Robotnik With 1 Hit.
FFBC21:01	Defeat Stage 8 Robotnik With 1 Hit.

Unofficial codes (user found)

Code	Effect
FFFE12:999D	Start wing fortress(Not sure about others) with 53(i guess) lives. Super Sonic mode Presents.
016398:0100	Very short jump height.
FFB03A:11C0	Sonic Generations spindash (partially breaks the game, dying softlocks the game)
004476:00XX	Player slot ID (When playing as Sonic & Tails). XX is the ID (Example: 004476:0025 changes Sonic to a ring).
00449A:00XX	Sidekick slot ID (When playing as Sonic & Tails). XX is the ID.
FFF600:00YY	Game Mode Modifier (YY: Mode). 00 - SEGA Screen 04 - Title Screen 08 - Demo 0C - Level 10 - Special Stage 14 - Continue Screen 18 - 2P Results Screen 1C - 2P Level Select Screen 20 - Ending Scene/Credits 24 - Options Menu 28 - Level Select Screen 8C - Pre-Level

If you want to make your own codes, see here. The format to edit those RAM values with PAR codes is this: FFXXXX:YY FF is FF, XXXX is the position of the data in RAM in four hexadecimal digits and YY is the value you want to put in in two or four hexadecimal digits. Remamber to convert your decimal value to hexadecimal first. For 2 Byte/16 bit values, put four digits in YY. If you need to enter values with four Bytes, you have to split it into two 2 Byte codes.