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Sonic & Knuckles (ソニック&ナックルズ Sonikku to Nakkuruzu?) is a platform game in the Sonic the Hedgehog series, developed by American studio Sega Technical Institute in collaboration with Sonic Team, and published by Sega for the Sega Mega Drive in 1994. It serves as the continuation to Sonic the Hedgehog 3. The game features unique "lock-on technology" which enables another cartridge to be plugged in via the socket on top.


Spoiler warning: Plot, ending details or any kind of information follow.



The title screen of Sonic & Knuckles.

Following immediately after the first part of the Angel Island incident, Sonic the Hedgehog has once again managed to stop the Death Egg's launch into space, thus leaving it to fall from the sky once more. Unfortunately, the Death Egg soon falls into the Floating Island again, this time right into the island's volcano. Meanwhile, after Sonic threw himself out into the sky following his last battle, he is swept by the wind into Mushroom Hill Zone, a lush forest with gigantic mushrooms. Seeing the still-intact Death Egg collide with the Floating Island's volcano, Sonic knows things are far from peaceful once more, as it will only be a matter of time before Dr. Robotnik restores the Death Egg once more.[3]

Gathering his resolve, Sonic prepares to set out for the Death Egg and destroy it once and for all. However, he is suddenly interrupted when he notices Knuckles the Echidna, the guardian of the Floating Island, who had been tricked into helping Robotnik, appear from a hidden door in the thicket. After carefully examining the vicinity, Knuckles disappears into the forest. Once sure that Knuckles is gone, Sonic emerges from his hiding place and opens the door Knuckles came out of with a nearby Switch. Inside the hidden room, Sonic is caught in an overflowing, dazzling light. Taking a closer look inside the light, he sees a Super Ring. Unable to quell his curiosity about what this ring could be, Sonic touches it, causing him to be taken to Hidden Palace Zone, a giant solemn hall with a pristine altar. Looking around, Sonic sees that the altar has a giant Chaos Emerald enshrined in it: the Master Emerald. Filled with questions, Sonic decides to set off to find the Chaos Emeralds, stop Dr. Robotnik from re-launching the Death Egg again, and discover the mystery of Hidden Palace Zone.[3]

Sonic facing Knuckles in Hidden Palace Zone.

Returning to Mushroom Hill Zone, Sonic eventually uses Robotnik's Flying Battery Zone to go to Sandopolis Zone. From there, he ends up in Lava Reef Zone, where the Death Egg is. However, the space fortress quickly uses its eye lasers to reactivate the volcano in an attempt to stop Sonic. Surviving this change in environment in spite of the odds, Sonic soon finds himself in Hidden Palace Zone again. There, he has a showdown with Knuckles. After Sonic manages to defeat Knuckles, the two witness Robotnik attempting to steal the Master Emerald to use it to power the Death Egg. Knuckles attempts to stop Robotnik as he flies away with the Master Emerald in the Egg Mobile, but Robotnik quickly gets away after he electrocutes Knuckles with his Egg Mobile's electric cords. Realizing that he has been fooled all along by Robotnik and that Sonic has actually been trying to do good, Knuckles takes Sonic to Sky Sanctuary Zone with a Warp Point. There, the two see the Death Egg successfully relaunch itself. WIth Knuckles too tired from the beatings he has received, Sonic goes on without him to stop Robotnik. As Sonic runs through Sky Sanctuary Zone, he has numerous encounters with Mecha Sonic, a robot created by Robotnik. However, Sonic manages to defeat the robot in each encounter and succeeds in catching up to the Death Egg and getting onboard.

With the Death Egg having made it into space, Sonic blasts through Robotnik's numerous contraptions throughout the Death Egg. After overcoming Robotnik's Death Ball, controlled by Robotnik himself, Sonic gives chase to Robotnik, who ends up bording his Giant Eggman Robo, a mech powered by the Master Emerald. After Sonic destroys the mech, a chain-reaction is triggered throughout the Death Egg that causes the entire space fortress to crumble and explode. The ending of the game will then depend on whether or not the player has collected all seven Chaos Emeralds:

  • If the player has not found all seven Chaos Emeralds, they will have defeated Robotnik and destroyed the Death Egg. With the Death Egg gone, Sonic falls down from the sky. Though he is saved by Tails in the Tornado, he loses the Master Emerald on the way down. Afterward, Tails will then fly himself and Sonic away. The player is then treated to a scene showing the Master Emerald in Robotnik's possession.
  • If the player has found all the Chaos Emeralds, they will have destroyed the Death Egg. However, Robotnik tries to make his escape with the Master Emerald in his Final Weapon In response, Sonic transforms into Super Sonic and pursues the doctor into The Doomsday Zone. After defeating Robotnik, Sonic and the Master Emerald will fall down from the sky, but are then saved by Tails in the Tornado. Afterward, the duo returns to the Floating Island and gives the Master Emerald back to Knuckles. The Floating Island will then start to float into the sky once more, and Sonic and Tails take their leave in the Tornado. The player is then shown a scene of an EggRobo emerging from some robot scrap.


While relaxing in Mushroom Hill Zone with the island's Animals, Knuckles is attacked by an EggRobo, who drops a bomb in front of him. Surviving the bomb's explosion whether through luck or sheer toughness,[4] an enraged Knuckles takes off after the EggRobo.

Knuckles fighting Super Mecha Sonic in Sky Sanctuary Zone.

After a series of encounters with the EggRobo, Knuckles finds himself in Sky Sanctuary Zone, where it is shown that the Floating Island has begun to fall from the sky once more. There, he is caught by the EggRobo using an Egg Mobile and its tethered hook, and is brought before a reactivated Mecha Sonic. As Mecha Sonic moves in to attack him however, Knuckles escapes, leaving Mecha Sonic to accidently destroy the EggRobo and the Egg Mobile. A battle between Knuckles and Mecha Sonic soon follows, with Knuckles emerging victorious. Not giving up yet though, Mecha Sonic retreats to a stolen Master Emerald, which explains why the Floating Island has begun to fall again. Despite using the Master Emerald to its advantage by harnessing its power repeatedly to assume a Super State, Knuckles manages to defeat the robot anyway. Upon Knuckles' victory however, their battle arena suddenly crumbles away beneath them. The ending of the game will then depend on whether or not the player has collected all seven Chaos Emeralds:

  • If the player has not found all seven Chaos Emeralds, Sonic will appear in the Tornado and catch an exhausted Knuckles, whom he will fly back to the Floating Island. Afterward, the Floating Island will fall into the sea and float on top of it. The player is then treated to a scene showing Mecha Sonic next to the Master Emerald before the former comes online and stands on top of the Master Emerald.
  • If the player has found all the Chaos Emeralds, Sonic will appear in the Tornado and catch Knuckles, now transformed into Super Knuckles, and the Master Emerald, both of whom he will fly back to the Floating Island. Afterward, the Floating Island will start rising into the sky once more.


Image Character Biography
Sonicthe20Hedgehog20320Japan.png Sonic the Hedgehog Runs around everywhere. The world's fastest hedgehog.[5]
Knuckles Sonic3.png Knuckles the Echidna A flying echidna. His nickname is Knuckle.[6]
CD Eggman.png Dr. Robotnik He's an evil genius scientist who will appear again this time. He's the best in the world at screwing up and being spiteful![6]
Tails 4.png Miles "Tails" Prower A fox with two tails who helps Sonic. He doesn't show up much this time?[7]


An example of gameplay as Knuckles in Mushroom Hill Zone, the first Zone in the game.

Sonic & Knuckles is a 2D side-scrolling platforming video game, which plays almost identical to Sonic the Hedgehog 3. Players can control either Sonic the Hedgehog or Knuckles the Echidna by selecting either of them in the title screen. Both characters can perform basic actions such as running and jumping. However, both have unique abilities that differ them from each other: Sonic retains his Insta-Shield from Sonic the Hedgehog 3, while Knuckles runs slower and jumps less, though he is able to glide and climb walls. Each character has their own story.

The main goal of Sonic & Knuckles is to pass a series of Acts in less than ten minutes. In these Acts, the player can find Rings, which basically work as the playable character's life source. When hit while having at least one Ring, the playable character will remain alive at the cost of losing all Rings. However, if the player gets hit without having any Rings, they will lose a life, or get a Game Over if they do not have any lives left.

Scoring system


Button formation Movement
Sonic Knuckles
Controlpadds.png left/right Run
Controlpadds.png up Look up
Controlpadds.png down Duck
A Button (Sega Genesis).svg / B Button (Sega Genesis).svg / C Button (Sega Genesis).svg Jump
Move + Controlpadds.png down Spin Attack
Duck + A Button (Sega Genesis).svg / B Button (Sega Genesis).svg / C Button (Sega Genesis).svg Spin Dash
Jump > A Button (Sega Genesis).svg / B Button (Sega Genesis).svg / C Button (Sega Genesis).svg Insta-Shield N/A
Jump > Holding A Button (Sega Genesis).svg / B Button (Sega Genesis).svg / C Button (Sega Genesis).svg N/A Glide
Controlpadds.png up/down N/A Wall Climb
START Pause the game



Gimmicks and obstacles


Playable characters

Non-playable characters



No. Sonic Knuckles
1 Hey Ho
(Mushroom Hill Zone)
2 Gapsule
(Flying Battery Zone Act 1)
3 Barrier Eggman
(Flying Battery Zone Act 2)
4 Guardian
(Sandopolis Zone)
5 Heat Arms
(Lava Reef Zone)
6 Egg Mobile-H
(Sky Sanctuary Zone)
7 Flying Eggman
(Sky Sanctuary Zone)
8 Red Eye
(Death Egg Zone Act 1)
9 Death Ball
(Death Egg Zone Act 2)


No. Sonic Knuckles
1 Jet Mobile
(Mushroom Hill Zone)
2 Hang Mobile
(Flying Battery Zone)
3 Egg Golem
(Sandopolis Zone)
4 Hot Mobile
(Lava Reef Zone)
Mecha Sonic
(Sky Sanctuary Zone)
5 Knuckles the Echidna
(Hidden Palace Zone)
Super Mecha Sonic
(Sky Sanctuary Zone)
6 Mecha Sonic
(Sky Sanctuary Zone)
7 Giant Eggman Robo
(Death Egg Zone)
8 Final Weapon
(The Doomsday Zone)


  1. Mushroom Hill Zone: A lush forest, with pump elevators, sticky vines, and filled with mushrooms that also serve as trampolines or parachutes. The miniboss is a woodcutter robot, and for the fight with Robotnik, the player must avoid the spiked bars and cannon shots while hitting the satellite-enhanced Eggman Mobile.
  2. Flying Battery Zone: The player is propelled to this flying fortress with electrified robots. The mini-boss looks like the Flicky-capsule and must be tricked into hitting itself. Robotnik is fought twice: first, he traps the player in an arena with a moving laser blaster on the ceiling, very similar to the Wing Fortress Zone boss. Then, it goes to an exterior platform which Robotnik latches onto from below and crawls along, spouting flame from the top of the pod every time the character attempts to jump over, and swinging upwards to be hit. This Zone is the only Zone where Knuckles faces Robotnik instead of Eggrobo, due to his access to the blimp being a last-minute decision.
  3. Sandopolis Zone: The heroes fall in this desert Zone, which houses a haunted pyramid which the character enters after beating the Guardian mini-boss. The boss, Egg Golem, must be hit in the face so Robotnik is exposed.
  4. Lava Reef Zone: The interior of a volcano, on which the Death Egg had crash-landed. The miniboss consists of mechanical hands that hit the player and orbs that shoot fireballs. Knuckles doesn't face a boss, but Sonic faces Robotnik in an invincible machine, which is only harmed by the landmines it drops.
  5. Hidden Palace Zone: The old Echidna temple. Knuckles just traverses the Zone. Sonic and/or Tails however, has to fight Knuckles. After he is defeated, Robotnik steals the Master Emerald to deceive the echidna; Knuckles decides to help the heroes instead.
  6. Sky Sanctuary Zone: A secret passage leads to these crumbly aerial ruins. Knuckles just faces his final boss, Mecha Sonic, which uses the Master Emerald to go Super. Sonic and/or Tails has to climb the Zone facing Mecha Sonic three times - one in the first flail-swinging mobile, another in a "Flying Eggman" and finally on foot.
  7. Death Egg Zone: Robotnik's space station, with electric traps, a vacuum chamber and sections with altered gravity. Two minibosses - Red Eye, a vulnerable laser shooting eye surrounded by spiked orbs, and Death Ball, which is only hit when the rotating shield bumpers are away - before facing a Robotnik-shaped mecha, Giant Eggman Robo.
  8. The Doomsday Zone: Only accessible as Super Sonic, this Zone has Sonic chasing Robotnik through space, avoiding meteors and missiles, and trying not to get his Rings depleted.

Special Stages

The Special Stages in this game are essentially the same as in Sonic the Hedgehog 3. There are a few differences though; mainly they are considerably harder than their Sonic the Hedgehog 3 counterparts. As well as having the blue, red and gray-and-red bumper spheres, a new kind has been introduced: yellow spheres act as springs and propel the character a set distance across the stage (a distance of five spheres, according to the US manual). Most yellow spheres are helpful, however there are a few that will catapult the player into red spheres, spelling failure for the player.

The Chaos Emerald appears at the end of the Special Stage just like in Sonic the Hedgehog 3, although when playing the complete game Sonic the Hedgehog 3 & Knuckles this will be a Super Emerald. The same rules apply throughout; enclosing a patch of blue spheres by touching the ones on the outside will turn all those spheres into Rings, and collecting all Rings in a stage awards a Perfect bonus of 50,000 points (an extra life). 50 Rings awards a continue.

The Special Stages in the Sonic & Knuckles Zones are not quite as straightforward as in Sonic the Hedgehog 3. The player will often have to perform clever tricks to complete them, such as making several jumps and turns in succession. As well as being harder in difficulty themselves, there are fewer opportunities to even attempt to get Emeralds. They all have to be collected before the end of Lava Reef Zone and the Giant Rings can be hard to find.

Bonus Stages

Similar to Sonic the Hedgehog 3, Sonic & Knuckles features two Bonus Stages: Slot Machine Stages[8] and Glowing Sphere Stages.[9] These can be entered by collecting a certain number of Rings and passing a Star Post, which will generate a Star Circle above the Star Post. The player must touch this Star Circle to enter a Bonus Stage. The Bonus Stage that is played depends on the amount of Rings the player had when they passed the Star Post. Unlike Special Stages, Bonus Stages serve only to get items, such as Rings or shields, and do not affect the story of the game.

Slot Machine Stages have the player in a field that is constantly spinning, similar to the Special Stages from the original Sonic the Hedgehog. Like those Special Stages, the Slot Machine Stages have various Bumpers, Jump Stands and Goals. At the center of the Slot Machine Stage is a gigantic slot machine. To activate it, the playable character has to enter some parallel bars on top of it. This will trigger a random combination of symbols which will cause the player to either earn or lose Rings, or simply not get anything at all. Slot Machine Stages do not have an end or a time limit, and the player has to touch a Goal to leave them.

Glowing Sphere Stages have the player traveling to the top of the stage using floating glowing spheres while having to escape from a field of energy that slowly rises upwards. When touching a glowing sphere, the playable character will spin around it. To progress, the player must tap A Button (Sega Genesis).svg B Button (Sega Genesis).svg/C Button (Sega Genesis).svg at the right time to launch themselves upward from the glowing sphere. Throughout the Glowing Sphere Stages are also smaller spheres that, when touched, will generate a random Gumball that will go upward. In addition, objects such as Rings, Bumpers and Flippers are found here as well. Glowing Sphere Stages end by either getting to the very top of their stage or touching the rising field of energy.



The soundtrack for Sonic & Knuckles was released as the album Sonic & Knuckles • Sonic the Hedgehog 3.

Lock-on technology

Logo of "lock-on technology".

Sonic & Knuckles utilizes "lock-on technology" that lets the cartridge plus the Mega Drive access data from Sonic the Hedgehog 2 and Sonic the Hedgehog 3 so that elements of both Sonic & Knuckles and the locked-on game are combined. To play these combined games, the hatch on top of the Sonic & Knuckles cartridge can be flipped open and the second game placed inside.

The Sonic the Hedgehog 3 and Sonic & Knuckles cartridges locked-on.

The lock-on technology was actually a way of making up for the fact that the developers could not meet the deadline for Sonic the Hedgehog 3. Originally, Sonic the Hedgehog 3 was to be released with Knuckles as a playable character, and with all the Sonic & Knuckles levels playable (the level select screen in Sonic the Hedgehog 3 features inaccessible Sonic & Knuckles levels and music for said levels can be played in the sound test). Time constraints forced them to split the project in two, releasing Sonic the Hedgehog 3 with the completed levels and continuing work on the uncompleted ones, plus adding the Super Emeralds and the lock-on feature. Sonic the Hedgehog 2 had once run into similar problems, resulting in the original Hidden Palace and several other levels being removed.[10]

Notably, no other video game in history features a "lock-on" feature quite like Sonic & Knuckles. Some NES games released by HES, as well as the Super Nintendo game Super 3D Noah's Ark, feature a cartridge port on the top to accept other games for the system, but this was purely to override the systems' respective lockout chips, as these games were not licensed by Nintendo. Some video game peripherals require being joined with a cartridge in a similar manner (i.e. Game Genie; GameShark), or transfer data between games (the Transfer Pak) but do not allow the "lock on"-style merging of data from two different video games. The technology was considered ahead of its time.

Sonic the Hedgehog 3

The title screen of Sonic the Hedgehog 3 & Knuckles.

Sonic the Hedgehog 3 & Knuckles is the combination of Sonic the Hedgehog 3 and Sonic & Knuckles in one large game. This would have been the Sonic the Hedgehog 3 that was originally meant to be released until time constraints caused the game to split into two. While gameplay remains identical, there has been several gameplay changes to accommodate the combination of the gameplay of both Sonic the Hedgehog 3 and Sonic & Knuckles, especially the level layouts. New features have being added as well, most notably the Super Emeralds.

Sonic the Hedgehog 2

The title screen of Knuckles the Echidna in Sonic the Hedgehog 2.

Knuckles the Echidna in Sonic the Hedgehog 2 is identical to Sonic the Hedgehog 2 (aside from a few changes to make it more playable with Knuckles) but with Knuckles now playable instead of Sonic or Tails. The title screen features Knuckles and the only option is "Press Start" (Options and the versus mode have been disabled but the level select is intact). There are no new Zones. The only differences in gameplay are that Knuckles can explore once inaccessible areas (where secrets such as 1-Ups have been added for Knuckles), some areas are harder because Knuckles cannot jump very high.

Sonic the Hedgehog and any other Sega Mega Drive game

Main article: Blue Sphere

The title screen of Blue Sphere.

Blue Sphere is an extra game that can be played by locking-on the original Sonic the Hedgehog or any other Sega Mega Drive game with Sonic & Knuckles with the same gameplay as the Special Stages from Sonic the Hedgehog 3 and Sonic & Knuckles. The game has over one million levels. If the player locks-on Sonic the Hedgehog with Sonic & Knuckles, they will be able to introduce a code to play any of the levels. However, by locking-on any other Sega Mega Drive game, they will be taken to a random level.



These are the achievements that are added to the player's Gamerscore on the Xbox Live Arcade version of Sonic & Knuckles.

Image Name Requirements Gamescore
Sonic Finale.jpg Sonic Finale Complete the game as Sonic. 25
Knuckles Finale.jpg Knuckles Finale Complete the game as Knuckles. 25
Please Continue.jpg Please Continue Earn a Continue in either a Bonus or Special Stage. 25
Complete Chaos.jpg Gettin' Super Collect all seven Chaos Emeralds. 25
Fast Freeze.jpg Chaos Emerald Collect a Chaos Emerald. 15
Hot Feet.jpg Hot Feet Finish the Lava Reef Zone. 15
Desert Runner.jpg Desert Runner Finish the Sandopolis Zone. 15
Grease Monkey.jpg Grease Monkey Finish the Flying Battery Zone. 15
Fun Guy.jpg Fun Guy Finish the Mushroom Hill Zone. 10
Extra Hedgehog.jpg Extra Hedgehog Collect 100 Rings. 10
Two Sided.jpg Two Sided Start the game once as each character. 10
Extra! Extra!.jpg Extra! Extra! Enter a Bonus or Special Stage. 10


Cover of Archie's cancelled Sonic the Hedgehog #291.

The main storyline of the Sonic the Comic series in between issues 47 and 53 is loosely based on the plot of Sonic & Knuckles, although with several changes.

Archie Comics made a tie-in of the game in Sonic & Knuckles, which was the second issue of Sonic Special comic books, loosely based on the plot of the game. It has also been confirmed that the events of Sonic & Knuckles have taken place in the Post-Super Genesis Wave timeline. The game's plot would have been adaptated in Sonic the Hedgehog #291 as the fourth and final part of the "Genesis of a Hero" storyline, but was ultimately cancelled before its release.




  1. メガドライブ カートリッジ(セガ発売) (Japanese). Archived from the original on 2020-07-20. Retrieved on 2021-12-23.
  2. 2.0 2.1 ソニック&ナックルズ セガ Wii(R) バーチャルコンソール公式サイト (Japanese). Retrieved on 28 January 2015.
  3. 3.0 3.1 Sonic & Knuckles (Sega Mega Drive) Japanese instruction manual, pgs. 12-13.
  4. Sonic The Hedgehog 4. Sega. Archived from the original on 12 May 2013. Retrieved on 27 October 2017.
  5. Sonic & Knuckles (Sega Mega Drive) Japanese instruction manual, pg. 8.
  6. 6.0 6.1 Sonic & Knuckles (Sega Mega Drive) Japanese instruction manual, pg. 9.
  7. Sonic & Knuckles (Sega Mega Drive) Japanese instruction manual, pg. 10.
  8. Sonic & Knuckles (Sega Mega Drive) United States instruction booklet, pg. 18.
  9. Sonic & Knuckles (Sega Mega Drive) United States instruction booklet, pg. 17.
  10. GameSpy: Sega's Yuji Naka Talks!
  11. Matthew Felix. Highest Score In "Sonic & Knuckles" (Sega Genesis). Recordsetter. Retrieved on 25 January 2015.
Sonic & Knuckles

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