- Not to be confused with Sonic the Hedgehog Extreme or the LCD game Sonic the Hedgehog Extreme Boarding.
Sonic X-treme is an unreleased platformer game in the Sonic the Hedgehog series. It was originally developed by Sega Technical Institute for the Sega Mega Drive, but was moved to the Sega 32X and eventually to the Sega Saturn and intended to be released around Christmas of 1996, but after many problems it was finally cancelled in 1997. Had it been finished, it would have been the first fully 3D Sonic game and the first original Sonic title developed for the Sega Saturn. This was the second Sonic game to be cancelled on the Sega Saturn, with the other being Sonic Saturn.
Multiple storylines were considered during the game's production, all of which were documented by Chris Senn on his website, the Sonic Xtreme Compendium.
- Sonic has until sundown to make his date with Tiara, the beautiful Manx Kitten-Princess. Their choice of a romantic spot makes for an adventurous journey as obstacles and enemies of all sorts plague Sonic’s path. The longer it takes him, the darker it gets and the more miffed Tiara will be in the end... Regardless of how long Sonic's trek lasts, he’s in for a BIG surprise in the end. Good luck, Blue Boy!!!
- Sonic wants to meet up with Tiara for a date, though the distance between them presents a bit of a problem. Sonic hangs in his Knothole crib, while Manx-baby chills in her pop's Kingdom a thousand males away!!! Sonic's got to race into and over many secret hills and valleys to get to his love. Tiara waits calmly, but cameo footage reveals her increasing impatience. The longer he takes, the more miffed she'll be when he arrives. Sonic figures a little necklace endowed with 7 certain Chaos emeralds would make a nifty gift to cheer her up. Unfortunately, via his Sneaky Spy Satellite (S3), egg-boy Robotnik gets wind of Sonic's chivalric endeavor and sets out to stop him.
- Dr. Robotnik decides that it's a great time for his new SuperDooper MegaRay Cannon. Tested on impulse power, the Cannon beamed a secluded forest in Mobius, causing its trees to rip from the ground and float in various orientations in the sky. Filled with devilish glee after a few more successful experiments, Robotnik schemes a way to stop Sonic from stealing the Emeralds AND to trap him forever! Having developed a spring- switch device to control the rotation of the floating walkways, Dr. Robotnik plans a series of puzzles and then sets the Cannon to FULL power, zapping the entire planet! When the boom and flash of light fades, Mobius is transformed! Huge chunks of wood, plant, metal and even whole houses, cars, etc.-- All ripped up, floating angellically[sic] in various angles in the sky! What a trip!
- So now, to complicate the distance/time issue, Sonic has a warped "twisted" world to navigate through that's filled with Robotnik's badniks! And to think that all Sonic wants is a nice, quiet good old-fashioned date! It's going to be more than half the fun getting there...
- Dr. Robotnik infects Sonic with a deadly Doom virus. Robotnik himself was previously infected and his plan is to trick Sonic into getting the cure and then snatch it away. Sonic meets Professor Boobowski, the only man in Mobius who can save him. He tells Sonic that he needs to collect the cure ingredients from different worlds as quickly as possible. Professor Boobowski takes the ingredients from Sonic as he gets them and begins preparing the wonder cure. Robotnik kidnaps the professor just prior to Sonic acquiring the last ingredient. Disguised as Boobowski, Dr. Robotnik tries to trick Sonic into handing over the final ingredient. Sonic recognizes the trap and then the two titans battle it out for a climactic ending fight!
- For thousands of years the "ChaosDoom," or Element Legion lay trapped, suspended in a state of lonely silence within the Master Chaos Emerald, watching seasons in the outside worlds come and go, generations birth and die.
- Dr. Ivo Robotnik, convinced there was some ultimate power within, succeeded in breaking the Emerald, providing a long-awaited exit for the ChaosDoom. No longer trapped, they waste no time in spreading their evil throughout Mobius and its surrounding dimensions.
- Initially (and in this game) though, all that takes affect is the DoomVirus, the poisonous atmosphere suitable only for the ChaosDoom. Any living creature coming in contact with the atmospheric rays of the broken Master Emerald fall into sickness, and eventually wither sway- Unless the Cure is found in time.
- Robots and creatures made of Metal, Stone or Wood are controlled by and serve as initial hosts for the ChaosDoom. Even Robotnik's Boss Robots do their bidding. All of these machines are bent on destroying Sonic, for he alone poses a threat to ChaosDoom.
- ChaosDoom's main problem is that in order to fully escape the clutches of the Master Chaos Emerald, they need TIME. Not a subscription to the magazine, but maybe a year to fully develop outside of their "egg."
- To the ChaosDoom, the longer Sonic can be delayed or even eliminated the more time they have to develop. Protecting the Acts with robots and the Cure Items with big, huge and nasty Bosses will hopefully accomplish this.
- Long ago, there was an evil man named Ivo Robotnik. He spent his time building robots that built smoky factories that churned out more robots with one goal: To take over the world. Thank goodness for one courageous creature. Enter Sonic, a fast and furious little hedgehog intent on having fun in the sun. Through the use of his wits and speed, Sonic was able to defeat the evil Robotnik and stop his domination. With help from the creatures of the world, Sonic jettisoned Robotnik to a galaxy far, far away – Hoping the rotund recluse would start his life anew.
- For years the world enjoyed peace. The air was clean and the creatures were safe. No more robots. No more terror. But one day, things changed. Creatures began disappearing from their homes without a trace. More and more dark shapes moved soundlessly through the night. A shadow engulfed the world and everyone knew something bad was about to happen...
- Sonic, on vacation in the Ice Caps, is snowdashing back to the lodge. Taking turns and jumps at high speeds, the little blue hedgehog is a streak of swiftness. As Sonic drops down the final frozen run, he notices something strange. There is no bridge! "What the--?!" gasps Sonic as he skids, arching to a stop beside a crystal chasm. Sonic wipes his brown[sic] in relief.
- Suddenly, a huge black spider-like shape rises from the ravine. Sonic leaps in panicked surprise as the scene fades to black...
- ...Sonic wakes up to find himself captured by this "Space Balloon," a pod designed by Robotnik to trap life forms for future use. Sonic has been traveling millions of light-years in the Space Balloon returning to Robotnik's massive Death Egg. Once Sonic realizes what's going on, he spindashes the heck out of the pod's computer panels, sending it hurtling toward the Jade Gully jungle planet...
- After Robotnik's defeat at the Floating Island, things returned to normal for Sonic and his friends. Robotnik however, had not been idle, and returned with an even grander scheme to conquer the world.
- Robotnik has rebuilt his Death Egg fortress, larger than Sonic's entire world! So powerful is its gravity that it can rip planets from their orbits. Already several planets orbited the huge fortress, and Robotnik would not rest until Sonic's world was in his clutches as well!
- Already the world is being drawn to the Death Egg. Sonic has to act quickly to stop Robotnik. Tails has managed to create a working teleport pod that can send Sonic to the Death Egg. There was no time to contact Knuckles, so Tails will stay behind and operate the teleport pod and Sonic will travel to the heart of the Death Egg and destroy it.
- But as Sonic was teleporting, one of the small planets surrounding the Death Egg changed course and intercepted Sonic! Sonic found himself on a strange world, surrounded by Badnik robots! Already the inhabitants of this world had been captured and changed into his evil minions. Robotnik had prepared a cunning trap, and Sonic had walked right into it.
- Everything had gone as Robotnik had planned. He knew that Sonic would try to get to his new Death Egg, and had changed the creatures called Mips into Badniks. Then by controlling the planet's orbit, he had led Sonic right into his trap!
- "HA! HA! Now I've got you, you spiky blue freak! You won't stop me this time!"
- Sonic must free the captive Mips, make his way to the new Death Egg, and destroy it quickly. If he fails, the world will belong to Robotnik forever!
Red Shoe Chronicles
The most known storyline was published in Electronic Gaming Monthly in 1995 as the "Red Shoe Chronicles". It involved new characters Professor Gazebo Boobowski and his daughter, Tiara, who are the keepers of the six magical Rings of Order, as well as the ancient art of Ring smithing. Gazebo and Tiara fear that Dr. Robotnik is after the six Rings of Order, and call on Sonic to get the Rings before Robotnik can.
To further the traditional Sonic formula, every Zone in Sonic X-treme was designed in a tube-like fashion, where Sonic would have been able to Spin Dash onto walls, thus changing the direction of gravity and the rotation of the level itself, much like the special stages in Knuckles' Chaotix. In addition, a fisheye-styled camera lens was put into place so players could see more of their surroundings at any given time.
At one point in the development process, there was a going to be a total of four playable characters: Knuckles the Echidna, Tiara Boobowski, Miles "Tails" Prower, and Sonic the Hedgehog. Each character would also have had a unique gameplay style, with Knuckles and Tiara respectively having the traditional, top-down and side-scrolling views. Sonic had the fisheye-styled lens over his levels, and Tails would play in first-person flight mode. Also, Sonic was to be equipped with a large set of new moves, including a Spin Slash, Ring throwing ability, Ring-powered shield, Sonic Boom, and a bouncing power ball. The Spin Slash move was cut out of the final version of the game due to it being too similar to the pre-existing Spin Dash.
Powerups were supposed to be contained in rotating spheres and included Shields. Shields were based on elemental powers, with each being stronger than the last, making rock-paper-scissors-styled "Circle of Power". The powers could be combined to make one of two "PowerShields":
- Elemental Circle of Power
- Metal (cuts Rock)
- Rock (shields from Lightning)
- Lightning (electrifies Wind)
- Wind (extinguishes Fire)
- Fire (evaporates Water)
- Water (rusts Metal)
- (Metal - Lightning - Fire)
- (Rock - Wind - Water)
Various other items had been planned for the game as well, with the following being listed on the Sonic X-Treme Compendium:
- Standard (1-up, Ring-up and Time-up)
- Shoes (Speed & Traction)
- Rings (Snake, Twist & Homing)
- Bomb (H-Ball)
There are few bosses known to have been under development for the game, these include:
- Darkpool Gorilla
- Emerald Cat (Jade Gully Zone)
- Fang the Sniper (Jade Gully Zone)
- Flame Falcon
- Guardian Sphinx Boss
- Jade Gold Boss (Jade Gully Zone)
- Mecha Mite
- Metal Sonic[note 1] (Metal Blade Zone)
- Metal Sonic Mark I
- Metal Sonic Mark II
- Metal Sonic Mark III
- Metal Sonic Mark IV
- Metal Sonic Mark V
Each Zone was to be made up of two regular Acts and a special, third boss Act, with the exception of the final Zone. The Castle of Light acts as the hub world from which the player can choose a level.
- Jade Gully Zone
- Emerald Clouds
- Wolf Den
- Bamboo Transit
- Red Sands Zone
- Giza Speedway
- Pyro Pools
- Tombs 'n Traps
- Metal Blade Zone
- Nightmare Bridge
- Sewer Shock
- Crystal Frost Zone
- Prism Chorus
- Galaxy Fortress Zone
- Death Egg Zone
- Factory Robo
- Proving Grounds
- Megabase Control
- Unnamed Act 4
- Unnamed Act 5
Sonic X-treme was intended to be developed for several other game systems prior to the Sega Saturn. In its earliest conception, the game was set to be released on the Sega Mega Drive, with production carrying over to the Sega 32X under the name Sonic Mars. The game was to be developed by Sega Technical Institute, the U.S.-based developer from which Sonic Team created Sonic the Hedgehog 2, Sonic the Hedgehog Spinball. After the release of said games, the Sonic Team members in America returned to Japan to work on the next Sonic games, along with NiGHTS into Dreams..., thus leaving the highly regarded studio without its original staff.
The Sega 32X version of Sonic X-treme was short lived, having been designed by Michael Kosaka before he left the company in mid-1995. This left the production team without a lead. Sega of America would soon instruct the studio to make the game for their next cartridge based console, which never ended up seeing the light of day. No development kits or technical information were ever provided, therefore development for Sonic X-treme on this mystery console never truly begin. While still somewhat working with the idea of a 32X release, it was quickly decided that the game would require much more powerful hardware to cope with the new engine.
With Sonic X-treme's production being shifted to the Sega Saturn, two separate engines were being created for use. The first was to be used in the boss levels, and required free-roaming capabilities. Programmer Christina Coffin was hired by Sega and tasked with creating the boss level portions of the game, with her being suggested to use a different viewpoint from the main game. The second game engine would be used in the regular levels, with each of the four planned playable characters to use a different camera angle. This project was led by lead designer Chris Senn and programmer Ofer Alon. The two engines were developed in parallel to each other, eventually leading to separations in the studio as there were essentially two games being produced. From a code standpoint, the two programs shared global memory to remember the game state and use a process called "executable chaining" to switch between themselves.
For the boss level engine, several perspectives, such as top-down and side-scrolling, were prototyped to create a more interesting view of the boss battle areas, while still using the pre-rendered Sonic sprite assets used in the main game's engine. This program began to evolve into almost a game of its own using NiGHTS into Dreams... as a source of inspiration, trying to stay closer to its 2D roots by adopting a 3D but side-scrolling viewpoint, which was more fluid and lent itself to the fast moving gameplay of previous Sonic titles. As production went on, the boss gameplay prototypes adopted a more pastel color scheme and organic flow of the inspirational NiGHTS game, causing some divided opinions amongst team members that felt originality was being sacrificed. The music and sound effects used in the boss engine came from the Japanese version of Sonic the Hedgehog CD.
The other side of the hall's work on the main engine was going smoothly, being produced on PC with the intent to port the software to the Saturn. Unfortunately, when Alon and Senn tried porting their gameplay engine to the Saturn, they encountered a multitude of problems, such as the game running in 3-4 FPS with only four colors. The game development studio Point of View was then recruited to assist in the game's technical development, beginning with porting an older prototype of the game to the Saturn.[note 2] The same problems would be encountered here. Some time after this, Alon was taken off the project, with Point of View becoming the main developers. To demonstrate the reasoning for such drastic actions to Alon and Senn, Point of View's technical director, Robert Morgan, showed them the demo created by the studio. Senn recalled that "they showed us the Sonic sprite we were already using floating in the upper-right of the screen, a checkerboard ground, a rotating shaded polygonal shape floating in the air and maybe a ring sprite animating. For all that we had created, to throw all that away for such nonsense. Amazing." After seeing this, Alon and Senn separated from Point of View's production team to continue developing Sonic X-treme as a PC game. As known from the last leak of Sonic X-treme, Point of View would go on to create a new game engine with a completely different source code.
While checking in on the game's progress in March 1996, Sega of Japan representatives were so impressed by the Coffin's boss engine that they requested the entire game be made on that instead, being labelled as "Project Condor". By this point in development the team was running short on hands, and as Point of View had not gotten much further than their initial demo, it all had fallen on the original Sonic Xtreme project team of Senn, Alon, and Coffin to finish the game. The NiGHTS into Dreams... engine was brought up as being potentially used for the Sonic X-treme main game-play, and Bernie Stolar, then president of Sega of America, told them in April 1996 to "consider it done." With the following weeks seeing work speed along with the use of new tools, production was suddenly halted when informed that Yuji Naka himself had threatened to quit if the NiGHTS engine was used any longer.
Development picked up again and it seemed the game's deadline for release would be met after all, with a playable demo of Coffin's boss engine being featured at E3 in May 1996. This was due to the boss engine never having used code from NiGHTS into Dreams..., therefore being much further in development than its main game counterpart.
This was, of course, just nine months away as the Christmas deadline was imposed so that the game could to go up against both Super Mario 64 and Crash Bandicoot alongside NiGHTS. A major change made at this point in the project was replacing the pre-rendered Sonic sprites with a 3D model, made by Kunitake Aoki from Sega of Japan. Coffin, who had been working nonstop to get the project out, came down with pneumonia. Around the same time, Senn was hospitalized due to illness brought on by his own absurd work hours. Both had moved out of their respective apartments and were living in the studio in order to get the game out on time by the end of the game's life. With both main programmers removed from the project, the loss caused the game to be indefinitely delayed and Mike Wallis, head producer at Sega Technical Institute, was forced to inform management that the game would not be released by its deadline.
The project was officially cancelled in August 1997, with Sega of America deciding to discontinue both the main Saturn version and the PC port. Focus was then switched to an alternative project: the Sega Saturn port of Sonic 3D Blast.
Over this strange history of Sonic X-treme's development, there were essentially five separate games designed:
- Sonic Mars: Michael Kosaka's design for the Sega 32X.
- Sonic X-treme: Chris Senn and Ofer Alon's gameplay engine with Chris Coffin's boss engine for the Sega Saturn.
- Sonic X-treme: Chris Senn and Ofer Alon's PC engine.
- Project Condor: Chris Coffin's later boss engine for the Sega Saturn.
- Sonic Extreme: Point of View's engine for the Sega Saturn.
The first contribution related to Sonic X-treme was in 1999, when Ross Harris released almost every sprite of Sonic used in the game.
A disc of a test engine for X-treme exists, with a copy having been sold at auction to an anonymous collector in September 2005. A high-quality gameplay video was expected to be released by the end of the year, through only an animated GIF of the gameplay was released to the community. The disk image was finally leaked on 17 July 2007. This prototype is actually Sonic X-treme early in it's conversion to Project Condor. An exclusive feature in this prototypes are blue crystals that throw the player up into the sky when interacted with. This prototype is often called the "718 prototype", as "SONIC J.G 7.18" was written on its disk (implying that the prototype's build date is 18 July 1996). The background music in the prototype is Quartz Quadrant's good future theme from the Japanese version of Sonic the Hedgehog CD.
In early January 2006, the game's director, Chris Senn, opened a forum based on the game on his own message board. He then began revealing large amounts of the game's development history to the public, including videos of early animation attempts, a mock-up of Tiara's gameplay, concept art of the characters, and more. Furthermore, he posted a large amount of previously unreleased concept music related to the title, along with receiving permission by Hirokazu Yasuhara to post the original level designs from the Sonic Mars point in development. Most of this information was posted on the Sonic X-treme Compendium website, which officially went online on 5 April 2006. The site has since become inaccessible, with only archived versions being viewable.
Later in 2006, a Sega Saturn Software Development Kit was leaked online that contained models from the Saturn version of Wipeout, a Saturn tech demo of Virtua Fighter 3, and models from the Project Condor era of the Sonic X-treme. These include a Green Hill Zone ground model, a monitor model with a picture of Sonic and Amy on it from Sonic the Hedgehog CD, the Sonic and Metal Sonic models from the Project Condor era.
In 2009, a large amount of files from Sonic X-treme, called "PackageX", was released. The package included textures and levels from the game, along with a level viewer to see and explore the levels in an unplayable format. There were two exclusive characters in this package: Chaz and Gabby, but Chris Senn has confirmed they were used as test art in a personal side project that was just using the Sonic X-treme engine.
In November 2014, a member of ASSEMbler Games called "Jollyroger" discovered some material from Point of View studio, which included some unreleased betas for their games. Amongst the material, there were multiple prototypes of Sonic X-treme game engines. The first one, "v37", doesn't have the fisheye and was played on the PC. Here, the player can use the "World Rotation" gameplay mechanic, implemented by Ofer Alon, by spinning into walls and slopes. v37 was released to the public in October 2015. The second version, titled "v40", functions as both a PC game and a Saturn disc image file. It does feature the fisheye lens. The Saturn version of v40 is a working continuation of Point of View's broken effort to port an older engine of the game to the Saturn. The level editor for a prototype titled "v53" has also been recovered, but not the game engine itself. Level editors for the other two demos were found as well, although they are unable to run on modern computers. An exclusive feature of these beta versions Sonic's ability to infinitely jump, which could possibly be used for debugging purposes. The final playable prototype found is a Point of View developed version dated 14 July 1996, with it using completely different source code and featuring physics similar to the first three Sonic games. In this version, Sonic explores Jade Gully Zone's second Act, with Debug Mode being accessible by pressing Start + on the gamepad. Unlike the previous prototypes, here the player can collect Rings and defeat enemies, along with being able to be hurt by said enemies with Rings will fling out upon contact.
In 2006, Chris Senn started Project S, an effort to complete the game unofficially. However, he later stated that it will be an original fan game heavily inspired by Sonic X-treme, rather than a straight resumption of the unfinished project. On 12 January 2010, Senn announced that Project S was cancelled:
- "Many people worked very hard throughout the project’s three-year and three-month life cycle. Making any product is extremely difficult, and Project S was no exception. Working for free and online with a wide range of experience, skillsets, availability and dedication just didn’t work out for the team responsible for Project S. The hope is that the successes the team earned along the way are complemented by lessons learned that, unfortunately, led to our collective inability to reach a public release."
Live-action/CGI hybrid film
In August 1994, Sega of America, with permission from Sega of Japan, signed a deal with Metro-Goldwyn-Mayer Pictures and Trilogy Entertainment to produce a live-action animated film to tie in with Sonic X-treme. In May 1995, screenwriter Richard Jefferies pitched a treatment, Sonic the Hedgehog: Wonders of the World, to Sega. The treatment saw Sonic and Dr. Eggman escape from the game and into the real world, where Sonic would collaborate with a boy to stop Eggman. No agreement was reached and the film was canceled. Jeffries, with permission from Sega, pitched his treatment to DreamWorks Animation, but it was rejected.
A Christmas special based-on the animated show Adventures of Sonic the Hedgehog titled "An X-Tremely Sonic Christmas" was in development to promote the new game. However, instead of being cancelled when the game was dropped, the episode was simply reworked into "Sonic Christmas Blast", being given a new title to promote the Sonic game that did come out in time for Christmas, Sonic 3D Blast.
The conceptual soundtrack by Chris Senn was posted on the Sonic X-treme Compendium, Chris Senn's website dedicated to Sonic X-treme development. It was created to inspire Howard Drossin, the composer behind Sonic the Hedgehog Spinball, who would make the official soundtrack.
|x01 Magmatropolis||Chris Senn||1:29|
|x02 Tombs-n-Traps||Chris Senn||1:00|
|x03 Volcano X||Chris Senn||1:30|
|x04 Mummy Madness||Chris Senn||1:01|
|x05 Pharoah Den||Chris Senn||1:30|
|x06 DiscoPyre||Chris Senn||1:14|
|x07 Jewel Keeper||Chris Senn||1:42|
|x08 Islam Prophet||Chris Senn||0:56|
|x09 Giza Speedway||Chris Senn||1:04|
|x10 Crimson Crypt||Chris Senn||1:01|
|x11 Pyro Pools||Chris Senn||0:39|
|x12 Gaurdian Sphinx||Chris Senn||1:16|
|x13 Darkroads||Chris Senn||1:00|
|x14 Necropolis||Chris Senn||0:54|
|x15 Nightmare Bridge||Chris Senn||0:56|
|x16 Black Harbor||Chris Senn||0:55|
|x17 Smog Tower||Chris Senn||1:37|
|x18 Concrete Pits||Chris Senn||1:01|
|x19 Streets of Gold||Chris Senn||1:36|
|x20 Shadow Market||Chris Senn||0:50|
|x21 Underdrowned||Chris Senn||1:00|
|x22 BigBadWolf||Chris Senn||0:51|
|x23 Assault Station||Chris Senn||1:24|
|x24 Sewer Shock||Chris Senn||0:41|
|x25 Spiral Staircase||Chris Senn||0:40|
|x26 Proving Grounds||Chris Senn||1:04|
|x27 Mesh Machine||Chris Senn||1:02|
|x28 Technoweb||Chris Senn||0:40|
|x29 Iron Program||Chris Senn||1:15|
|x30 Eery Descent||Chris Senn||0:49|
|x31 Factory Robo||Chris Senn||0:48|
|x32 MegaBase Control||Chris Senn||0:51|
|x33 Titan Tank||Chris Senn||1:32|
|x34 Shiver Plains||Chris Senn||1:01|
|x35 Cryogenesis||Chris Senn||1:02|
|x36 Prism Chorus||Chris Senn||0:40|
|x37 Frozen Falls||Chris Senn||0:49|
|x38 Borealis||Chris Senn||1:34|
|x39 AquaDome||Chris Senn||0:40|
|x40 Murk Trench||Chris Senn||0:32|
|x41 Sealanterns||Chris Senn||1:14|
|x42 Coral Realm||Chris Senn||0:45|
|x43 Pearl Mountain||Chris Senn||1:24|
|x44 SiniSquid||Chris Senn||0:58|
|x45 Petroleum Proteus||Chris Senn||1:09|
|x46 Ultra EelecTrick||Chris Senn||0:59|
|x47 Emerald Clouds||Chris Senn||0:57|
|x48 Bamboo Transit||Chris Senn||1:03|
|x49 Floating Stones||Chris Senn||1:13|
|x50 Wolf Den||Chris Senn||0:56|
|x51 Skyhive||Chris Senn||0:49|
|x52 Royal Mobius||Chris Senn||0:54|
|x53 Options||Chris Senn||0:45|
|x54 Credits||Chris Senn||1:03|
|x55 PC Demo||Chris Senn||1:14|
|x56 Lost Boss||Chris Senn||1:22|
|x99 Base Jump||Chris Senn||1:49|
|x99 Castle of Light||Chris Senn||1:36|
|x99 Circuit Centerfold||Chris Senn||3:12|
|x99 Cortisone||Chris Senn||1:36|
|x99 Crystal Valley||Chris Senn||2:22|
|x99 Death||Chris Senn||0:07|
|x99 Destructor||Chris Senn||2:41|
|x99 Disciples||Chris Senn||3:18|
|x99 FantaSea||Chris Senn||3:55|
|x99 Mobius||Chris Senn||2:20|
|x99 Pickup1||Chris Senn||0:06|
|x99 Quake Caverns||Chris Senn||2:28|
|x99 Rebirth||Chris Senn||3:20|
|x99 Shield of Discovery||Chris Senn||5:41|
|x99 Spirit Gates||Chris Senn||3:17|
|x99 Tarantulas In The Grass||Chris Senn||3:04|
|x99 Teal Trouble||Chris Senn||1:55|
|x99 Tile Tracks||Chris Senn||2:54|
|x99 Zone Done||Chris Senn||0:07|
|Space Queens (Promo)||Chris Senn||2:32|
|Space Queens (Extended)||Chris Senn||3:18|
- Sonic X-treme's level editor, engine, and internal name are called SonicBoom and SONCBOOM in recovered prototypes.
- The game was originally based on the Saturday morning cartoon series while it was still under the title Sonic Mars, with it supposed to include the Freedom Fighters. However, all elements from the TV series were dropped when the project became Sonic X-Treme.
- If this game had been released, it would have been both Fang the Sniper and Amy Rose's second official 3D appearances, the first being Sonic the Fighters.
- Late in development, Chris Coffin briefly toyed with the idea of Amy Rose as a playable character, so she modified most of Sonic's the sprites to look like her. The hedgehog would have thrown Rings to attack, with the player risking their life in doing so as Rings were the main source of energy. Tiara had been long scrapped by this point, so Amy would have become the first female playable character in a main series Sonic game.
- In the 718 prototype, there are two easter eggs: The first one is if some layers are disabled, the ground texture from the Metal Sonic boss battle from Metal Blade Zone can be seen. The second secret is that, by pausing the game and pressing , a game over screen will be displayed before the game resets. This game over screen uses the theme from the Japanese version of Sonic the Hedgehog CD.
- The story about the "Rings of Order" was made up for a magazine while the real plot was still in progress.
- An ice cream bar, radio and cassette player were made to promote the game, but were discontinued due to its cancellation. However, the same products were later re-released in normal Sonic the Hedgehog-themed packaging.
- Though referred to as "Mecha Sonic" in images, the actual game files and developers call him Metal Sonic.
- This specific version is now known as "v40", having been originally developed by Ofer Alon in early 1996.
- Senn, Chris (21 August 1995). Sonic Twist. Sonic Xtreme Compendium. Archived from the original on 26 February 2008. Retrieved on 12 May 2022.
- Senn, Chris . SonicBOOM. Sonic Xtreme Compendium. Archived from the original on 16 April 2009. Retrieved on 12 May 2022.
- ; Wheeler, Richard Sonic DOOM. Sonic Xtreme Compendium (17 January 1996). Archived from the original on 2 December 2008. Retrieved on 12 May 2022.
- Senn, Chris . SonicPC. Sonic Xtreme Compendium. Archived from the original on 1 March 2009. Retrieved on 12 May 2022.
- ; Wheeler, Richard SonicPC. Sonic Xtreme Compendium. Archived from the original on 23 February 2009. Retrieved on 12 May 2022.
- Sonic Xtreme - Frequently-Asked Questions. Q: What are the Rings of Order, and what did they do?. Senntient. Archived from the original on 17 March 2011. Retrieved on 12 May 2022.
- Topic: Knuckles!. Senntient Forums: Xtreme (19 January 2006). Archived from the original on 18 July 2011.
- Senn, Chris . Knuckles Overhead Camera Tests. Senntient. Archived from the original on 29 December 2011. "A technical test to explore camera rotation and shadows with a top-down view."
- Senn, Chris . Tiara's side-view test. Senntient. Archived from the original on 11 June 2010. "A technical test to explore the concept of 2D gameplay using 3D graphics with the addition of 3D playground changes."
- Senn, Chris . Sonic Xtreme: Frequently-Asked Questions. Senntient. Archived from the original on 18 March 2009.
- Senn, Chris (18 April 2006). The Sonic X-Treme File Archive: home > boss. Archived from the original on 14 October 2008.
- Senn, Chris . Darkpool Gorilla Boss. Archived from the original on 2 December 2008.
- Senn, Chris . JadeGold EmeraldCat Mips (JPG). Archived from the original on 10 October 2007.
- Senn, Chris . Mecha Mite Boss. Archived from the original on 2 December 2008.
- Senn, Chris . Death Egg Zone 5: General Description & Design (JPG). Archived from the original on 9 October 2007.
- Horowitz, Ken (11 June 2007). Developer’s Den: Sega Technical Institute. Sega-16.
- "Whatever happened to... Sonic X-treme". Retro Gamer (Imagine Publishing) (Load 22): 36. Archived from the original.
- Edge Staff (14 April 2014). The Making Of: Sonic X-treme. Edge.
- Sonic X-Treme Timeline (as provided by Mike Wallis). Lost Levels. Archived from the original on 13 June 2003.
- Fahs, Travis (29 May 2008). Sonic X-Treme Revisited. IGN.
- Allen, Jonathan . Spotlight: Sonic X-Treme. Lost Levels.
- Slingerland (13 January 2010). CHRIS SENN PUTS AN END TO "PROJECT S". Sonic Stadium.
- Senn, Chris . Xtreme. Senntient Forums: Xtreme.
- Senn, Chris (24 September 2007). The Sonic X-Treme File Archive: home > music. Archived from the original on 14 October 2008.
- Davis, Ashley (19 November 2008). What could have been: Sonic X-treme. Destructoid. Archived from the original on 11 November 2020.
- AM/FM Radio Promo For UNRELEASED Sega Saturn Game SONIC X-TREME! NEW! Hedgehog. eBay (20 November 2020). Archived from the original on 26 November 2020.
- Vintage Sega Sonic the hedgehog Xtreme portable stereo cassette tape player. eBay (2 August 2017). Archived from the original on 26 November 2020.
- at Senntient (archived)