This is our own personal chronological timeline for Sonic the Hedgehog and his universe, created and researched by the Sonic Metropolis Team. We spent many hours, days, and even months to figure out which timeline could be the most canon and logical one we can make. Keep in mind though that it is not perfect, because we also came to the conclusion that creating a 100% true Sonic timeline is impossible, because there will be always little details or facts which will speak against this timeline. However, this does not stop us from making the most logical timeline we can offer. 

Sonic Metropolis
Chronological Timeline

You also need to keep in mind that not all games or cartoons can be always canon of course, so we also sorted games out which are canon, and which are not. Furthermore we will not include Mini-, Party- or mobile games just as all other different sonic game versions ported from the one console to the other, and same for national changed versions [We always pick the original JAP variant]. If you however disagree with something, or you think you might found some issues with our timeline, you can always contact us about that on discord where we could discuss about what we might missed then.

Team Sonic Metropolis
Graphical Form
Timeline Version
Public V.1.2.7

The Main Chronological Timeline

Sonic the Hedgehog 1
1991
This is where it all began. Robotnik attempts to capture the Chaos Emeralds and harness their unlimited power while using creatures of the land to power his robot army, but Sonic the Hedgehog sets out to stop him. The 7th Chaos Emerald was not yet found. Upon defeating Robotnik, the Chaos Emeralds currently held by Sonic scattered across the land.
Sonic CD
1993
After hearing news that Little Planet appeared, Sonic traveled to Never Lake, but found out however that Little Planet had been captured by Dr. Robotnik. Sonic needed to collect all the Time Stones, rescue Amy Rose and beat the robot duplicate of himself created by Robotnik, Metal Sonic. In the end, he successfully accomplishes his mission.
Sonic the Hedghog 2
1992
Dr. Robotnik once again tries to get the Chaos Emeralds. More bold than ever, the Doctor has created a massive instrument of destruction, the DEATH EGG. Sonic is determined to destroy the Death Egg together with his new friend Miles Tails Prower while searching for all the Chaos Emeralds before Dr. Robotnik obtains them. They find out about the existence of the 7th Chaos Emerald which Sonic manages to use for the first time and transform into Super Sonic and safely descend from a climactic battle in space with Dr. Robotnik.
Sonic the Hedgehog 3
1994
After the defeat in Sonic the Hedgehog 2, Robotnik discovers the Master Emerald and its Guardian Knuckles the Echidna. Robotnik tricks Knuckles into believing that Sonic is the villain. Knuckles neutralized Sonic's super form with his power and took all the Chaos Emeralds from him. Sonic and Tails however move forward to foil the Doctor's plans of rebuilding the Death Egg. Along their journey, they recapture the Chaos Emeralds.
Sonic & Knuckles
1994
The events happen directly after the previous game. After stopping Robotnik from fully relaunching the Death Egg, Sonic and Tails continues his journey to stop him for good. Knuckles still sees Sonic and Tails as the enemy and brawls with them. Upon being defeated, Knuckles realizes he has been tricked after witnessing Dr. Robotnik attempting to steal the Master Emerald. Unable to stop him, the three team up in efforts to catch up and defeat the Doctor and his Death Egg and restore the Master Emerald to its proper place. Sonic battles the Doctor in one of their most intense encounters. Meanwhile Knuckles fights Super Mecha Sonic to retrieve the Emerald. In the end, all Chaos Emeralds and the Master Emerald to their place on Angel Island.
Knuckles' Chaotix
1995
Knuckles found out that Robotnik was up to something again, which made him lead to meet with Mighty the Armadillo, Espio the Chameleon and Vector the Crocodile for the first time. Now its up to them, to stop Robotnik's Plan to use the Dark Rings to power his badniks.
Sonic 3D Blast
1996
Learning that the seven Chaos Emeralds are somewhere on Flicky Island, Dr. Eggman attempts to locate them but can not find them. He notices however that the flickies seem to be able to teleport to other worlds using large rings. Believing they have some powerful connection, Eggman decides to turn them into robots using his new machine Dimension Ring Generator. Too late to the scene, Sonic, Tails, and Knuckles arrive to flickies already being placed in robots. Sonic makes the decision to go about freeing all the flickies from every robot, getting to the chaos emeralds before Dr. Eggman, and defeating the Doctor.
Sonic Adventure
1998
The Characters have aged a bit and turned from classic characters into modern ones. Sonic, Tails, Knuckles, Amy, E-102 Gamma and Big the Cat go through their each own Adventure in which Eggman (also known as Robotnik) and his plans provide the backbone of the story. Beside this a new mysterious water Creature named Chaos and a central guide for our heroes named Tikal appear. Eggman plans to use the super powerful creature to take over Station Square by gathering the Chaos Emeralds and having Chaos absorb their power.
Sonic Adventure 2
2001
Shadow the Hedgehog, the supposedly "Ultimate Life Form" does appear, who was first mistaken with Sonic by most people. Eggman tries to collect all the Chaos Emeralds together with Shadow and Rouge the Bat, to power the giant canon from the Space Colony ARK for his evil plan. But Sonic and his friends set out to stop this. Amid all the chaos amongst the clash between the story of hero vs dark, all of the stories central characters must work together to stop this imminent threat.
Sonic Advance
2001
Once again, Eggman goes with his classic plan to capture all the Chaos Emeralds and to take over the world just to get once again beaten by Sonic and his friends.
Sonic Advance 2
2002
Eggman kidnaps Tails and Knuckles. When Sonic is on the way to save them, he meets Cream the Rabbit who also wants to rescue her Mother Vanilla the Rabbit from Eggman, so they teamed up to save the day.
Sonic Heroes
2003
Metal Sonic use his newest power to copy DNA of other characters, capture Eggman and create a mass fleet to become the robot overlord. Sonic, Tails and Knuckles united in Team Sonic, Shadow, Rouge and the new character E-123 Omega in Team Dark, Amy, Cream and Big in Team Rose and also already existed team of detective agency Team Chaotix (Vector, Espio and Charmy) work together to stop Metal Sonic’s plan.
Shadow the Hedgehog
2005
Shadow is determined to find out more about his past, when he suddenly meets Black Doom, who technically is his father. He searches for the Chaos Emeralds with hope of getting answers to his past. In his journey for truth, he interrupted by conflicts amongst the Eggman army, Black Arms, GUN and Sonic and company. Presented with decisions on who to help accomplish their goal along with accomplishing his mission of finding the truth.
Sonic Battle
2003
Sonic found a strange robot, who can absorb the Chaos Emeralds and copy the movements of other characters. Sonic names this robot Emerl and tries to become its friend. Emerl creates close bond with Sonic, Tails, Rouge, Knuckles, Amy, Cream and Shadow but because of Eggman’s evil scheme Emerl lose his mind and Sonic were forced to destroy him.
Sonic Advance 3
2004
Emerl does appear once again as Gemerl, who was rebuilt by Eggman with Emerl's Data. This time Eggman used Chaos Control to tear the world apart.
Sonic Rush
2005
Blaze the Cat, the princess and guardian of the ancient artifacts - the Sol Emerlads makes her way into Sonic's Dimension to retrieve the Sol Emeralds which were stolen by Doctor Eggman. Doctor Eggman Nega - the counterpart of the original Eggman from Blaze's Dimension was trying meanwhile to capture the Chaos Emerlads, while Sonic does prevent him from that. Blaze the Cat learns with time the importance of Friendship, with the help of Cream the Rabbit and Sonic. At the end they ally together and beat Doctor Eggman and Eggman Nega.
Sonic Rivals
2006
Eggman use a special camera to turn Angel Island with a Master Emerald, Tails and Amy in it into cards, Rouge chase him but also got trapped into the card. Sonic in a purpose to save his friends, Knuckles, who wants to save the Master Emerald and Shadow, who tries to solve the mystery of what is going on and also save Rouge chasing Eggman. In the end, Eggman is not Eggman we knew at all – he is actually Eggman’s "counterpart" – Eggman Nega. Silver also came back from the "future" chasing Eggman Nega. At the end, Sonic, Knuckles, Shadow and Silver defeat Eggman Nega and retrieve all captured objects from the cards.
Sonic Rivals 2
2007
Sonic and Tails got alerted because someone stole a lot of chao from Sonic world. Chasing the stealers they find out, that this is Silver and Espio who stole them. Silver try to save chao from Eggman Nega, who wants to release a powerful being Ifrit to destroy the modern timeline, Espio helping him because he feels, that Silver is a good person. In the same time Rouge collect the Chaos Emeralds for the unknown person using Knuckles' help, who lost Master Emerald again, in the same time Shadow by the Dr. Eggman's task using Metal Sonic's help tries to stop Rouge and Knuckles, because person Rouge is working for is Eggman Nega and he wants to use Chaos Emeralds to open the portal to the Ifrit dimension. In the end, portal was opened but the chao was saved by Sonic and Tails, all characters fights Ifrit while he is still not on his full power and defeat him. which left Eggman Nega trapped in Ifrit's Dimension.
Sonic Rush Adventure
2007
This time, Sonic and Tails end up in another Dimension by a mysterious storm at night while flying with the tornado when suddenly a lighting did hit them. When they awake on a remote island, they meet Marine the Raccon who longs to be a sailor. While exploring the surrounding islands, they did encounter a band of pirates lead by the robotic Captain Whisker, who are after an ancient artifact known as the Jeweled Scepter. Soon after that Sonic, Tails and Marine did meet Blaze the Cat once again, she reveals to them that they have accidentally traveled to her dimension during the storm, and that she has been attempting to stop the pirates for some time, so Blaze and Sonic agree to work together and retrieve it. At the end it turned out to be that Eggman and Eggman Nega were behind the whole plan to steal the Scepter. Sonic and Blaze defeat them, which leads to Sonic and Tails to go back Home again.
Sonic and the Secret Rings
2007
Sonic falls asleep while reading Arabian Nights. Afterwards, he somehow mysteriously ends up in this Arabian World. There he meets Shahra who asked him to save their world from the evil being Erazor Gin, by collecting all 7 World Rings. At the end Sonic defeats Erazor and seals him away forever.
Sonic World Adventure aka Sonic Unleashed
2008
Dark Gaia is unleashed by the power of the Chaos Emeralds which Eggman strips from Sonic in an all out brawl unlike any other between the two. Awakened prematurely, Dark Gaia energy spreads across a broken planet, its Creatures terrorizing the whole world. Sonic who was trapped by Eggman's newest weapon is transformed into the werehog, holding a small fraction of Dark Gaia's power. The Chaos Emeralds were drained of their positive energy during this event. At night, Sonic takes this new form and returns to his normal self during the day. A new and friend Chip accompanies Sonic to help find his memory and again and defeat the Dark Gaia and Dr. Eggman.
Sonic and the Black Knight
2009
Sonic manages once again somehow to end up in the World of a story book, this time from King Arthur. When he arrived there, he met a Mage with the name Merlina. With her help, Sonic found the legendary living sword Caliburn. After that Sonic needed to pass some test given by the Lady of the Lake to become a real Knight and defeat Arthur. After completing the tasks including beating Arthur, Merlina started the complete destruction with the Scabbard. With the help of the Lady and the Knights however, Sonic managed to defeat Merlina as well and return the world to its normal state again.
Sonic Colors
[DS] 2010
Eggman builds Eggmanland in Space, which has the look of a giant theme park, but behind the scenes he is capturing Aliens called wisps who have with special abilities. Sonic and Tails set out to foil the Doctor's heinous crime. Along the way, they discover that Sonic and the wisps are able to join their powers and perform feats the blue blur had never performed before.
Sonic Generations
[3DS] 2011
A mysterious being the Time Eater shows during Sonic's surprise Birthday party, capturing all Sonic's friends and turning the world into a empty and colorless place. However, Sonic recieves some extra help when he runs into his younger self and younger Tails. In a race to restore time and life, it is up to the modern Sonic and the classic Sonic from the past or other dimension of time to save their friends and destroy the Time Eater.
Sonic Lost World
2013
Sonic and Tails in another mini mission to take back the critters Eggman captured to power his army, discover the Lost Hex. Eggman who already knew about this place, enslaved the Deadly Six which are creatures living there called Zeti. After the Deadly Six betray Eggman though, Sonic teamed up with Eggman for some time to stop their evil plans especially after Tails is captured as well. After they are thwarted, Eggman double crosses Sonic and Tails only to be defeated yet again.
Sonic Mania
[Other Dimension]
2017
In this Dimension, classic Eggman aka Dr. Robotnik finds the Phantom Ruby and uses it for his own plans. Sonic, Tails and Knuckles are now set against Robotnik who now can send them to different spaces and places in time. In addition, he boasts a new elite set of robots the Hard-Boiled Heavies that he uses to fight Sonic and company. After the final battle, classic Sonic was teleport to the events of Sonic Forces where he serves there to aid the Resistance. Due to their victory, classic Sonic could return to his timeline. Being sent back to Angel Island, Sonic runs into Mighty the Armadillo and Ray the Flying Squirrel who are captured. He rescues them and teams up with them to beat Robotnik who possesses the Phantom Ruby again. In another battle against time, the resurrected "segasonic" team put an end to the Doctor's plans.
Sonic Forces
2017
Eggman finally wins. Sonic was defeated and Eggman managed to take over the entire world. Because of that a resistance group was found, lead by Knuckles and Amy. They made it a priority to first rescue Sonic so that he can join the fight against Eggman. and infinite the jackal, a mercenary of Eggman's who utilizes the phantom ruby to alter reality.. Classic Sonic from the other Dimension and a new Recruit take part as well in the fight. Together they defeat Eggman and his Army and did save the world.
Team Sonic Racing
2019
Sonic and his Friends get invited to race against each other by a mysterious Tanuki called Dodon Pa to win special cars. Since no one truly knew what Dodon Pa was really planning, everyone was suspicious of him and his motives. The suspicion level soared when Eggman, Metal Sonic, and Zavok joined the races. With progression in the story, it is made clear that Dodon Pa simply wanted to create the ultimate engine which he made to be powered by teamwork from the very unique race tournaments he hosted which involved racing as teams. However, it also made clear that Eggman's plans change when he learns of this information and believes he could use that energy to power and promote his machines. Naturally, the team saves Dodon Pa and themselves when a hasty Eggman uses the still unstable engine.

Notes About the Main Timeline

● Neither Classic Sonic nor Robotnik knew about the 7th Chaos Emerald in Sonic the Hedgehog 1. The 7th Chaos Emerald was later discovered in Sonic the Hedgehog 2.

● Some People consider Sonic the Hedgehog 2 being the second game in the Main Timeline, but that is incorrect. In Fact Sonic CD’s concepts and its project already started directly after Sonic the Hedgehog 1, and was planned to be released before Sonic the Hedgehog 2, but it was delayed. More evidence is manifested when you take note that the idle and some running sprites are the same as Sonic 1; in addition, the spin dash took a different form. In the original version you see also at the end of the game an image that shows up with Tails on it saying “See You Next Game” as reference to Sonic the Hedgehog 2.

● Sonic the Hedgehog 3 and Knuckles is a game which contains Sonic the Hedgehog 3 and Sonic & Knuckles. It has some differences though compared to the versions before, like you can play Sonic the Hedgehog 3 levels with Knuckles, or use Tails in the Levels of Sonic & Knuckles.

● To the Point of Sonic Adventure, all the characters aged a bit. Keep in Mind though that Sonic and his Friends are non-human, they have a complete different age system and play by other rules than humans do. Its unknown at what age the character are considered to be mature enough to be viewed as adult. What we know though is that all non-human characters become much faster mature than humans.

● The Shadow who appeared for the first time in Sonic Adventure 2 is the same Shadow who also did show up in all other Sonic Games. He did not die in Sonic Adventure 2; he was saved by Eggman and recovered.

● Even though Sonic the Hedgehog 2006 isnt canon when it does come to its plot or Silver’s and Blaze’s origin, it has some elements which do lead into some character development, for example that Shadow the Hedgehog and Omega did start now to work for GUN.

● Silver the Hedgehog is a character who came from the “Future” and even though its confirmed by SEGA that he indeed is from the future, it is very unlikely that this could work. (Warning, the following words are now only the opinion of the Administrator). Time Travel does not work at all in any points of being logical, especially in the Universe of Sonic the Hedgehog. Since Time Travel means automatically that a character can exists a billion times and even more just by going one millisecond back in time and taking the past version with you. Beside that even if you could go back in time to “fix things”, it will not change anything anyway from the current future you are from because each life form is or was an unique existence with its very own history and cannot be simply replaced, removed, or moved from one moment to another. That is why we Team Sonic Metropolis believe that Silver does not came from the future but from another Dimension instead, even though he believes he is, but he is likely wrong.

● Eggman Nega from Rush and Rivals are most probably two different personalities with different backstory and characteristics. Its basically impossible to have another logical explanation rather than Eggman Nega from Rush and from Rivals to be different characters, since there is no other way to explain their completely different backstory. We cannot name Rush or Rivals uncanon because of how both game do heavily affect the further Sonic game universe.

● Since the Events of 06 were deleted, Silver was introduced once again to Sonic and his friends in Rivals, in a more proper canon way.

● When it comes to the Storybook games “Sonic and the Secret Rings” and “Sonic and the Black Knight”, they are canon because of some little references to them in future Sonic games like Generations. However the only logical way of Sonic ending up in those 2 Worlds / Dimension, is that everything was only a Dream of his. We can exactly see how Sonic did fall asleep at the beginning of “Sonic and the Secret Rings” while he was reading just before that the Book of “Arabian Nights”. Also people do tend to dream about other people in different forms, that would also explain why many of his “new” companions or friends in those 2 games were his classic real friends. Furthermore, only Sonic knows about these happenings which further confirms that it was only a dream. So it might make sense that “Sonic and the Black Knight” was also just some imagination of Sonic while sleeping.

● Instead of the Wii Version, the DS one of Sonic Colors is probably the real canon one. Both games have the same plot, but however the handheld version does show you much more story elements and does also include more character interactions just as some other details like the appearance of the Mother Wisp. And on top of that, here is a little fun fact; Sonic Colors on the DS was originally meant to be called “Sonic Rush 3”. The Gameplay style does make it also quite obvious.

● Similar to Sonic Colors, we do consider the 3DS version of Sonic Generations to be more canon than the other versions. It doesn’t have the stage “Crisis City” but does come with “Water palace” instead, which makes in total more sense considering that Blaze & Silvers origin is from Rush and Rivals.

● In Sonic Generations we meet Classic Sonic again, but most people mistake him with the Classic Sonic from “Sonic the Hedgehog 1” – “Sonic & Knuckles”. They are not the same individual, the Classic Sonic from Generations does come from another Dimension instead of the past, it was also later on confirmed in “Sonic Forces”.

● The Classic Sonic from the other Dimension had his first appearance in “Sonic Generations”, and afterwards he was playable in “Sonic Mania” & “Sonic Forces”.

Events Which Might Maybe Happened

These listed Events / Games count as being maybe part of the main timeline. However there are still either not enough or no proofs at all to confirm it.

SegaSonic the Hedgehog
1993
Dr. Eggman utilizes a large tank of his to kidnap Sonic, Ray, and Mighty, transporting them to Eggman island which contains countless traps and hazards. The team trio work together to escape this catastrophe to get to Eggman Tower. Upon reaching the Control Room, Dr. Eggman initiates a self-destruct sequence for the entire isalnd. The team manages to escape the island before sudden death. Eggman escapes as well but plummets to the ocean once his Egg Mobile runs out of fuel.
Sonic Chaos
1993
Game Gear (Japanese) While Sonic and Tails were on an adventure, Dr. Eggman manages to obtain one of the chaos emeralds. This caused the rest of the meralds to scatter across South Island. With the emeralds not supplying power, the island began to plummet to the sea. Once word got out, Sonic and Tails rush to resolve the chaos and defeat Dr. Eggman. Game Gear (Western) Dr. Eggman steals the red chaos emerald to construct weapons of mass destruction such as nuclear bombs and laser powered weapons. This caused the remaining emeralds to lose power and travel to a parallel universe. South Island descended, adn Sonic and Tails set off to undo Dr. Robotnik's actions and restore balance to the universe. Master System A year passed since the six Chaos Emeralds were restored to South Island. However, a big explosion rocked the island. Flicky the Bluebird travelled to North Cave to discover that the emeralds were missing. The island began to fall from the skies. Dr. Eggman emerged, possessing the red chaos emerald, proclaiming that he would conquer the world once he obtains the remaining emeralds. Without hesitation, Sonic and Tails challenged his plans and began the mission to retrieve the emeralds, defeat Robotnik, and save the world.
Sonic Triple Trouble
1994
Sonic and Tails are on an adventure to capture the 6 chaos emeralds before Dr. Robotnik does. Nack the Weasel, later addressed as Fang the Sniper, and Knuckles appear in this game.
Sonic Shuffle
2000
Sonic, Tails, Knuckles, and Amy are in an unfamiliar environment called Maginaryworld. A fairy named Lumina requests help, explaining that the place is the world of people's dreams and the power comes from the Perfect Preciouston. The enemy Void shattered the sacred stone, causing chaos in the world to unfold. Lumina Flowlight and the rest of Maginaryworld are depending on Sonic and company to restore the stone and bring back Lumina.
Sonic Riders
2006
Jet, Wave, and Storm while in hopes to discover the hidden treasure as the gaze at the special cube is interrupted by Eggman who claims he needs the seven chaos emeralds to utilize the cube to summon the Babylon Garden. In Eggman fashion, he mentions SOnic as well to start a feud. Meanwhile, Sonic, Tails, and Knuckles are in search of a lost chaos emerald. Running into Jet and his team, they discover that they have the very emerald they were after. Soon the team runs into an announcement from the Doctor who created a Grand Prix, offering all chaos emeralds to the winner. After races and scuffling between the teams, Eggman manages to steal the key to obtain the treuasre for himself after the chaos emeralds have powered the cube and revealed Babylon garden. The Babylon Rogues unleashed a powerful ancient spirit named Babylon Guardian. The defeat of this entity reveals the secret treasure which surprised everyone. The feud of SOnic vs. Jet continues.
Sonic Riders Zero Gravity
2008
Sonic learns of the legend of the "Ark of the Cosmos", a powerful object that uses matter to control gravity. The Babylon Rogues, Sonic's rivals, are also after this artifact. The war between the two resurrects again.
Sonic Chronicles: The Dark Brotherhood
2008
Split into 10 chapters, the first six chapters follows suit in Sonic's world where the team is trying to find Knuckles and to keep the Master Emerald from being stolen by Marauders. The final four involves Sonic and the team traveling to the dimension Twilight Cage in order to resolve a new threat and confront the alien species that lives there.
Sonic Free Riders
2010
Eggman hosts a World Grand Prix, disguising his identity as King Doc. He secretly collects racing data from all the competitors. He later unveils his identity, revealing he gathered data in order to beat them all in a race. The data helped none at all as the data recieved was false because the machine used that was supposedly Team Dark's E-10000B was actually Metal Sonic. He fed the Doctor false info. So Metal Sonic decided to race Sonic only to use. Eggman finally admits there was no reward, but the racers were still joyful that they had fun along the way.

Events Which Might Maybe Not Happened

These listed events and games are very unlikely to be canon in the same Universe as the main timeline, either because of crossovers or big plot holes.

Sonic Drift
1994
Sonic, Tails, Amy, and Dr. Eggman participate as rally contestants in racing vehicles to beat their opponents to the finish line in typical 90's racing style.
Sonic Drift 2
1995
With more characters from the franchise, the participants race along more courses with several powerups and obstacles to beat their opponents to the finish line.
Sonic R
1997
While vacationing, Tails notice a sign advertising a World Grand Prix and tries to convince Sonic that they should join. Contemplating whether he wants to or not considering races did not really interest him, he notices the sign mentions that Dr. Robotnik is participating. He was gone in an instant, heading for the races. Little does he know that this was a lure to get Sonic in the race so that Dr. Robotnik could defeat Sonic while he searches for the Chaos Emeralds that he knows is nearby. In addition, Knuckles joins the race to be apart of the action and Amy joins in hopes that winning will impress Sonic.
Sonic & Sega All-Stars Racing
2010
In this side adventure, the events simply follow characters from across the SEGA universe clashing in all out racing contests. Of course, Sonic and company as well as Eggman are involved in these races with other beloved game characters from Beat and B.D. Joe to Ryu and Aiai.
Sonic & All-Stars Racing Transformed
2012
Well known SEGA characters return once more along with new characters from other universes to participate in one of the most daring and adventurous racing events ever. Players transition from boats, cars, and planes mid-race to be the first to the finish. In addition, players can brawl it out with opponents in battle mode or play other modes available in this massive kart racer.
Mario & Sonic at the Olympic Games
2007
Mario, Sonic, and an assortment of their friends and enemies compete in a large number of Olympic and fantasy events to win medals.
Mario & Sonic at the Olympic Winter Games
2009
This entry in the Mario & Sonic Olympic series allows player to assume character from either franchise and compete against others in Winter Olympic events.
Mario & Sonic at the London 2012 Olympic Games
2012
Bowser and Dr. Eggman, who had yet to receive invitations, employ various tactics to mess with the other competitors in the Olympic events. In this sequel, players can again choose from a large assortment of characters to participate in countless sports events for victory.
Mario & Sonic at the Sochi 2014 Olympic Winter Games
2014
This entry in the series involves teams of characters from both franchises in which each team must complete an area consisting of 4 events and one boss battle. In the 2nd event, you face off against a Mii and the last against a boss.
Mario & Sonic at the Rio 2016 Olympic Games
2016
With 20 characters of choice, players participate in various sports and Olympic events. However, it is noted that characters were restricted to certain events
Mario & Sonic at the Olympic Games Tokyo 2020
2020
The cast of characters return for Olympic event action. Unique to this entry is the ability to play 2D versions of events with 8 bit Mario characters and 16 bit Sonic characters all in 2D art style graphics. These events only feature eight playable characters. The remaining characters are not featured in these select events.

Sonic Boom Universe

The Sonic Boom Universe is not connected with the main timeline in any way.

Sonic Boom Rise of Lyric
2014 [Story Version 1]
Sonic, Tails, Amy, and Knuckles encounter an ominous and powerful snake villain name Lyric who plans to create powerful army war robots with the "Chaos Crystals" and create a world of metal and robots. In a large scuffle amongst Team Sonic, Eggman, Metal Sonic, and Lyric comes betrayal amidst the enemy forces and a struggle that the heroes overcome to defeat Lyric as well as Eggman.
Sonic Boom Shattered Crystal
2014 [Story Version 2]
Sonic teams up with Tails, Knuckles, and Sticks. Running into Shadow along the way to save Amy who had been captured by Lyric. In what seems to be a tug-of-war struggle between the two forces, the teamwork of Team Sonic comes out on top as they defeat Lyric and his numerous contingency plans.
Sonic Boom Fire and Ice
2016
Team Sonic is on a mission to prevent fissures' fire and ice elements from causing devastation to the world. Sonic and Amy gain fire and ice powers after rupturing a fissure. Simultaneously, they must also deal with Eggman's robot D-Fekt who has similarly limitless magnetic powers. In spite of Eggman constantly attempting to destroy Sonic and his friends, he, in the end, must be saved by Sonic.

Definitely Not Connected To Main Timeline

These listed events and games are not in relationship with the main timeline for sure

Tails Skypatrol
1995
Tails decides to go on his own adventure with out Sonic in this game. While travelling, he runs across a lonely island with a steel railroad across it. Believing Eggman was creating another base, he investigated. A lady naming herself the Witchcart dashes past along a railroad, declaring the island hers and that all dissenters would be turned to crystal. Tails sets out to rescue the animals before Witchcart gets to them.
Tails Adventure
1995
Western Tails begins his mini vacation alone after his adventure with Sonic.While resting on "Tails Island", he was woken by a loud noise and saw that the forest was engulfed in flames. Tails discovered an army of birds scattered across the island as well as a flying fortress. He set out to save the creatures of the island with little time to investigate the plans of the bird army. Japanese Before Tails ever meets Sonic, he lives in his research lab located on the south side of the beautiful Cocoa Island. During an afternoon rest, he was awakened by a booming explosion and a forest engulfed in flames. Flickies came, shouting about the arrival of the "Battle Kukku Empire." The leader Great Battle Kukku XV is looking for the Chaos Emeralds in order to dominate the world. In one of his most daring adventures, Tails notices the silhouette of an intimidating and enormous mecha in the distance and is determined to end this threat once and for all. This was Tails first adventure alone before Tails Skypatrol.
Sonic Blast
1996
While napping peacefully, Sonic was disturbed by a blinding flash from a nearby chaos emerald. The Emerald shattered into 5 pieces due to Eggman aiming incorrectly trying to destroy Sonic with a laser and hitting the emerald. Unperturbed, the Doctor was was pleased with the outcome as he planned to use the shard to fortify his new aerial base Silver Castle. Sonic waste no time in beginning to thwart his plans when Knuckles steps out from nearby and joins him in preventing Eggman from accomplishing his plans.
Sonic the Figthers
1996
The story sets a scene of dangerous robots appearing in places seemingly from nowhere. Suspecting its from the Doctor, Tails receives a video message from Espio showing that they are coming from the Death Egg. Sonic decides to use Tail single-seat rocket to travel there but 8 chaos emeralds must be inserted into it as a power supply. The emeralds were spread throughout the world, held by Sonic's friends (except one which was stole by Fang) to keep Eggman at bay and unable to use them. SOnic and Knuckles bicker over who is the strongest enough to ride Tails' "Lunar Fox" rocket. Tails breaks it up and declares that whoever wins the fight fair and square in a ring will ride the Lunar Fox. So the story follows the player of choice fighting each holder of a chaos emerald and making their way to the Death Egg where they fight a clone of themselves made by Eggman. Afterwards, the player must fight a surprise Metal Sonic. Upon defeating Metal Sonic, Death Egg II begins to malfunction, and the player must use the power of the chaos emeralds to defeat Dr. Eggman who is in his E-mech suit in only 15 seconds. You safely escape the exploding Death Egg II (including Dr. Eggman and Metal Sonic).
Sonic the Hedgehog 06
[Deleted Event] 2006
Silver the Hedgehog and Blaze the Cat live in the "Future" where everything is destroyed by Iblis. One day however they believe to get the chance to undo the destruction of the "Future" when a mysterious figure named Mephiles claims going back into the "Past" and destroying Sonic will prevent this future. Meanwhile Sonic is busy with rescuing Princess Elise from Dr. Eggman repeatedly to keep him form haenessing her power. Shadow becomes involved when he sets out to stop Eggman from his newest and more daring attempt to take over the world. When Sonic, Silver, and Shadow seemed to have rectified their situations and everything seemed all well, unexpected events occurred. In a master form of trickery, Mephiles made fools of everyone as he orchestrated each event in the story. After killing Sonic, Mephiles merges with Iblis to from Solaris and attempts to consume time itself. Sonic, Silver, and Shadow team up to end this disaster. With this story, the entire experience of the crew becomes erased from time when Elise must has only one choice but to put out the flame that is Iblis. The events of the story become erased with the exception that Silver's World is saved thanks to Blaze's sacrifice, who got sent to another Dimension with a new Identity, leaving this as only thing which was not reversed and erased thanks to the Power of the Chaos Emeralds in combination with the curse of Iblis. Nobody will remember any of these events though.
Sonic 4: Episode 1
2010
After the events of Sonic 3 and Knuckles (destroyed Death Egg and a safe Master Emerald), Sonic parts with tails to explore new environments. Dr. Eggman decides to revamp his old machines and take down Sonic. Sonic runs down the Doctor to his new location, the E.G.G. Station Zone. Naturally, Sonic defeats the Doctor and his new powered up Death Egg Robot. As a result, E.G.G. Station is left destroyed in the battle.
Sonic 4: Episode 2
2012
Several month after the events of Sonic 4 Episode 1, Little Planet, as appeared in Sonic CD, has finally appeared again. Dr. Eggman simply used his battles with Sonic as a coverup while he secretly planned his greater scheme. Because Metal Sonic was left on Little Planet after his defeat, he disappeared along with the floating paradise. ow that he has returned, Sonic recruits Tails and heads out through various environments to stop Dr. Eggman while witnessing a mechanical structure encasing Little Planet just as before. Even though the Doctor was resurrecting his domination of the planet, Sonic and Tails overcame the powered up Metal Sonic and Dr. Eggman. Upon defeating them, Death Egg mk.II drained its power and was left floating space while SOnic and Tails returned home in two escape pods. Little Planet is presumed to be left floating in space, trapped inside the Death Egg mk.II.

TV Shows And Movies

● Adventures of Sonic the Hedgehog (1993-1995)

● Sonic the Hedgehog [SatAM] (1993–1994)

● Sonic the Movie [Sonic OVA] (1996, 1999)

● Sonic Underground (1999)

● Sonic X (2003–2006) [Plot and Human Characters are not Canon, however this show does represent many characters excellent in their, behavior, life style, hobbies and relationships to each other, when it does come to canon terms]

● Sonic: Night of the Werehog (2008) 

● Sonic Boom (2014–2017)

● Team Sonic Racing Overdrive (2019)

● Sonic the Hedgehog [2020]

● Sonic Colors: Rise of the Wisps (2021)

Notes About TV Shows And Movies

● Adventures of Sonic the Hedgehog, Sonic the Hedgehog [SatAM] and Sonic Underground are cartoon shows which do show the biggest differences compared to the games, because they go into a completely other Universe direction than the games do. 

● Sonic Underground is the only cartoon which is based to be a musical-styled show with Sonic and company.

● Sonic Night of the Werehog is the only short listed here.

● Sonic X is not fully canon, however its confirmed that Sonic Team wanted to show us more of the private life of each character, how their daily life in free time is like, and generally get more deep characteristics out of Sonic and his Friends. Its plot and the human characters are NOT canon, however most of the characteristics, the relationships between Sonic and his Friends, the abilities or skills, the way they spend their free time, and the way they behave is canon.
Furthermore Its important to mention that the Japanese version is the original one. The EU and US version are heavily edited, where much is cut and changed in terms of conversations, fights, environment details, music and emotions.

● Sonic Boom does play in the Boom Universe obviously. Its not connected to any other Universe at all.

● Sonic the Hedgehog 2020 does give us once again another spin off as far as canon ideas. Its just as the most other cartoons or movies not canon. It is Sonic’s debut on the big screen and boasts the highest opening for a video game movie ever along with several other feats.

Comics and Mangas

To get on point, there are no canon Comics or Mangas out there for Sonic the Hedgehog. All Comics and Mangas do play in a completely different Universe and are not even in the slightest connected to the Main Timeline.

[Included : all Archie Comics, all Fleetway Comics, all IDW Comics, and different Mangas from Japan]

However, there may be some exceptions for some mini comics from SEGA, but these are only exceptions. In general there are no canon Comics or Mangas no matter its publisher.