Sonic Generations

Sonic Generations is a 2011 platformer video game developed by Sonic Team and published by Sega for the Xbox 360, PlayStation 3, Nintendo 3DS and PC. The game was made and released to celebrate the twentieth anniversary of the Sonic the Hedgehog series. The Japanese version has different subtitles: White Time and Space for the home consoles, and Blue Adventures for the 3DS version. All versions of this game can be played in stereoscopic 3D, but a 3DTV as well as a pair of 3D glasses are required for the PlayStation 3 and Xbox 360 versions, being the first game of the franchise to support stereoscopic 3D.

In April 2018, the Xbox 360 version of the game was made backwards compatible with the Xbox One and supports Xbox One X enhanced features.

Plot
In a past version of Green Hill, Classic Sonic is running until he hears a noise. Suddenly, the mysterious entity known as the Time Eater appears in the sky and the screen washes white.

In the present day, Sonic celebrates his birthday with his friends until the Time Eater disrupts the party, sucking everyone through various "time holes" and scattering them across different points in Sonic's past. Sonic tries to stop the monster, but is easily overwhelmed by its power. After regaining consciousness, Sonic finds himself in a strange dimension known as White Space, a realm where time and space end up after they have been 'erased' by being drained of color and life. Sonic rescues his best friend Miles "Tails" Prower and as they search for their friends, they encounter versions of themselves from the past, referred to as their "Classic" selves. As the two Tails determine that Time Eater's actions are damaging time and space itself, which is why it is white and lifeless, both "Classic" and "Modern" Sonic race through their history, restoring time to normal and rescuing their friends. They also realize at one point that the Time Eater's weakness are the Chaos Emeralds.

After restoring the worlds and collecting all the Chaos Emeralds, they discover that the mastermind behind the Time Eater is Eggman and his classic self, Classic Eggman, who was faking himself to be a victim of the Time Eater all along. He reveals that while drifting through space following the events of Sonic Colors, Eggman discovered the Time Eater, thinking about the idea to use its powers and decided to join forces with his past self to harness its power. Although the Time Eater manages to nearly defeat the two Sonics, the support of their friends and the power of the Chaos Emeralds allow them to transform into Super Sonic and Classic Super Sonic, and confront both versions of Eggman. Despite attacking with missiles, warping arms and slowing down time, the Sonics penetrate the Time Eater's core, destroying it. The heroes return to the present and continue celebrating Sonic's birthday. During the party, Classic Sonic, Classic Tails and Classic Knuckles travel back to their own world as everyone bids their farewells.

A post-credits scene shows the two Eggmen lost in White Space. The two argue as they search for an exit, discuss whether or not they ever defeat Sonic and contemplate if they should go back and get their teaching degree as opposed to continuing their misdeeds.

Playable

 * Sonic the Hedgehog
 * Super Sonic
 * Classic Sonic
 * Classic Super Sonic
 * Classic Tails
 * Classic Knuckles (Minami Luna's version only)

Allies

 * Miles "Tails" Prower
 * Classic Tails
 * Knuckles the Echidna (Console/PC/Minami Luna's version) (indirectly mentioned in 3DS version) (Cameo too)
 * Classic Knuckles (Minami Luna's version only)
 * Amy Rose (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Cream the Rabbit (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Big the Cat (Minami Luna's version only) (indirectly mentioned in 3DS version) (Cameo too)
 * Rouge the Bat (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Vector the Crocodile (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Espio the Chameleon (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Charmy Bee (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Blaze the Cat (Console/PC version) (indirectly mentioned in 3DS version) (Cameo too)
 * Marine the Raccoon (Minami Luna's version only) (indirectly mentioned in 3DS version) (Cameo too)

Supporting

 * Omochao (Optional guide) (Console/PC/Luna)
 * Cheese (Follows Cream) (Console/PC/Luna) (Cameo in 3DS version)
 * Chao (They appear in a Speed Highway mission and a City escape mission)
 * Animal friends (Flickies and other species must be rescued)
 * Orange Wisp (Console power-up for Modern Sonic)
 * Pink Wisp (Console/Luna power-up for Classic Sonic)
 * Red Wisp (3DS power-up for Classic Sonic)
 * Cyan Wisp (3DS power-up for Modern Sonic)

Cameos

 * Fang the Sniper - City Escape (Wanted poster)
 * Bean the Dynamite - City Escape (Wanted poster)
 * Bark the Polar Bear - City Escape (Wanted poster)
 * Mighty the Armadillo - City Escape ("Missing since 1993" poster)
 * Ray the Flying Squirrel - City Escape ("Missing since 1993" poster)
 * Chao - Speed Highway/City Escape/Crisis City/Radical Highway ("Chao in Space" billboard in Speed Highway, "Chao in Space 2" billboard in City Escape, "Chao in Space 3" for Crisis City, "Chao in Space 4" in Speed Highway's hub world section and a neon sign for Radical Highway) and Trophy room
 * Perfect Chaos - City Escape ("Chao in Space 2"; also a boss)
 * E-102 Gamma - Profile Card (3DS only, optional favorite character)
 * E-123 Omega - Speed Highway (road sign) and Trophy room; also a mid-rival
 * Death Egg Robot - Speed Highway ("Chao in Space" billboard in Speed Highway; also a boss)
 * Tikal - Speed Highway ("Chao in Space: The Search For Tikal" billboard)
 * Chip - Speed Highway (road sign) and Trophy room
 * Jet the Hawk - Speed Highway (road sign) and Trophy Room; also a rival
 * Wave the Swallow - Speed Highway (road sign); also a rival
 * Storm the Albatross - Speed Highway (road sign); also a rival
 * NiGHTS - Radical Highway (NiGHTS hotel 3DS and Luna's versions only)
 * Orbot and Cubot - (Eggman's flashback in the console/PC/Luna's version shows that he left them in space after the events of Sonic Colors)
 * White Wisps - Planet Wisp (In the beginning of both acts)
 * Mii - Profile Card, Wi-Fi Icon
 * Mephiles the Dark - Crisis City; also a boss
 * Dark Gaia - also a boss

Enemies

 * Doctor Eggman
 * Classic Eggman

Rivals

 * Classic Metal Sonic: Stardust Speedway/Casino Night
 * Shadow the Hedgehog: Final Rush/Radical Highway *Mid-rival: E-123 Omega (Luna's version)
 * Silver the Hedgehog: Crisis City/Tropical Resort
 * Babylon Rogues (Jet the Hawk, Wave the Swallow and Storm the Albatross): Metal City/Night Chase (Luna's version)

Console/PC bosses

 * Death Egg Robot: Death Egg
 * Perfect Chaos: Station Square
 * Egg Dragoon: Eggmanland

Nintendo 3DS bosses

 * Big Arm: Launch Base
 * Biolizard: Cannon's Core
 * Egg Emperor: Final Fortress

Final boss

 * Time Eater: Center of Time