I've seen many failed attempts at trying to establish Sonic's timeline, too many people put spin-offs with the series or Sonic X's story or even Archie's comicbook stories. This is probably the best timeline you'll read but I'm not sure if this is 100% accurate.
Sonic the Hedgehog 1(1991)
Sonic must stop the evil Dr. Robotnik from taking over the world.
Sonic the Hedghog 2(1992)
Sonic meets Miles "Tails" Prower for the first time in West Side Island but run into Dr. Robotnik who tries to take over the world once again.
Sonic CD(1993)
Sonic travels solo to Never Lake to view the mysterious Little Planet, little does he know that Amy Rose is already there waiting to meet him for the first time. To make things complicated, Dr. Robotnik has already chained Little Planet to Earth and now Sonic must free the planet and save Amy from Robotnik's newest creation, Metal Sonic, before it's too late!
Sonic the Hedgehog 3(1994)
Sonic and Tails travel to Angel Island, a mysterious island that floats above Earth, to stop Dr. Robotnik from repairing the Death Egg, however, this won't be easy as a red echidna named Knuckles is tricked by Robotnik into thinking Sonic is after the Master Emerald.
Sonic and Knuckles(1994)
The Death Egg falls back on Angel Island once again along with Sonic who must stop Robotnik from stealing Master Emerald, but Knuckles is back, and ready to try and stop Sonic once again.
Sonic 4: Episode 1(2010)
Sonic decides to go solo again, but finds Robotnik trying to take over the world again.
Sonic 4: Episode 2(2012)
Little Planet has once again reappeared and Robotnik takes it back like he has before and repairs Metal Sonic who has survived his last battle with Sonic, who has returned along with Tails to free Little Planet once more.
Sonic Adventures(1998)
After a long deserved vacation, Sonic, now a grown teenager, finds Robotnik(Now known as Eggman by Sonic and friends), trying to destroy the world with a new villian, Chaos. But to acomplish this, he needs the 7 chaos emeralds in order to do so. Sonic and friends must stop Eggman once again.
Sonic Adventures 2(2001)
Shadow is a black hedgehog created decades ago before Sonic was even born. Dr. Eggman decides to look into his grandfather's past experiences which leads him to infiltrate Prison Island and free Shadow from his long captivity. Shadow becomes a useful ally for Dr. Eggman to but Shadow will only grant his "wish" if Eggman brings the chaos emeralds to him on Space Coloy Ark. Meanwhile, Sonic tries to enjoy himself, only to find himself accused of being the black hedgehog. Now he must stop this confusion, Eggman's plans, and most importantly, Shadow.
Sonic Heroes(2003)
Sonic and his friends Tails and Knuckles recieve a letter from Eggman who lets them know that he is planning on conquering the world once again, now they must work as a team to foil his plans but little do they know that they will run into their other friends and rivals and that a returning evil has come back to have his revenge on Sonic.
Shadow the Hedgehog(2005)
Shadow must stop the Black Doom invasion from destroying the world and find out more about his mysterious past.
Sonic The Hedgehog 2006(2006 obviously)
Sonic must rescue Princess Elise from being kidnapped by Dr. Eggman, but Silver, a hedgehog from the future is told by a mysterious figure, that Sonic will become the cause of the end of the world. Silver comes to the past to stop Sonic from causing the disaster.
Sonic World Adventure or Sonic Unleashed(2008)
Eggman with his new fleet floating above Earth, attempt to take over the world but Sonic destroys the fleet and becomes Super Sonic to chase Eggman back to his flagship. Seemingly Eggman surrenders and Sonic is distracted while Eggman traps him and reverts him back to normal Sonic and then turns him into a werehog. He shoots the Earth which causes it to break into pieces and then sends Sonic and the emeralds droping back to the planet. Sonic with the help of a new found friend, Chip, must now rebuild the Earth and stop Eggman from awakening an ancient evil.
Sonic Colors(2010)
Eggman claims to have turned good and to prove it, he builds an interstellar amusement park. Sonic who is accompanied by Tails, thinks Eggman is up to something and explores the area to find that Eggman has stolen aliens and their planets. Sonic and Tails both must to free the aliens and their planets from Eggman's new plan.
Sonic White Spacetime or Sonic Generations(2011)
It's Sonic's birthday, and his friends planned a party for him. Their party is short lived when a time consuming monstrosity interrupts the party and kidnaps all his friends. While on his way to rescue them, he meets his younger self from the past and the two work together to stop whoever is up to this evil scheme.
This took up alot of space but let me know what you think or if I did anything wrong-Classicsonicawesome 22:21, March 23, 2012 (UTC)
GREAT!!! But CD can't come in between 2 & 3, because though time did come between them, there was not enough time between them to fit another adventure. Oh and you might not know, but Rush is canon because in Generations, Blaze's profile states that she protects the Sol Emeralds. But DON'T ask me about her plot hole!
71.42.151.123 23:01, April 4, 2012 (UTC)
Sonic's timeline is rather obsurce, as there are plenty of little, not-so-well-known sonic games that don't particulary fit into the sonic canon, however, I think our Sonic the Hedgehog series page does a good job of it. Myself 123 23:10, April 4, 2012 (UTC)