User:TheJoebro64/drafts/Sonic2

Sonic the Hedgehog 2 (ソニック・ザ・ヘッジホッグ) is a 1992 platform game developed by Sega Technical Institute (STI) for the Sega Genesis. It follows Sonic as he attempts to stop Doctor Robotnik from stealing the Chaos Emeralds to power his space station. Like the first Sonic the Hedgehog (1991), players traverse side-scrolling levels at high speeds while collecting rings, defeating enemies, and fighting bosses. Sonic 2 introduces Sonic's sidekick Miles "Tails" Prower and features faster gameplay, larger levels, a multiplayer mode, and special stages featuring pre-rendered 3D graphics.

After Sonic the Hedgehog greatly increased the popularity of the Genesis in North America, Sega directed STI founder Mark Cerny to start Sonic 2 in November 1991. Members of the original development team—including programmer Yuji Naka and designer Hirokazu Yasuhara—moved from Japan to California to join the project. Sonic 2 was intended to be faster and more ambitious than the first game. The development suffered setbacks, including language and cultural differences between the Japanese and American staff, and numerous levels were cut due to time constraints and quality concerns. As with the first game, Dreams Come True member Masato Nakamura composed the soundtrack.

Sonic 2 was widely anticipated, and Sega backed it with an aggressive US$10 million marketing campaign. It was released in November 1992 to acclaim and received numerous year-end accolades. Critics considered Sonic 2 an improvement over the first game and praised the visuals, level design, gameplay, and music, though the low difficulty level and similarity to its predecessor were criticized. Sonic 2 broke video game sales records and became the bestselling game of 1992 in North America and Europe, grossing over US$450 million. With six million copies sold worldwide, it is the second-bestselling Genesis game behind the original Sonic the Hedgehog.

Sonic 2 solidified Sonic as a major franchise and played a major role in keeping Sega competitive during the console wars of the fourth generation of video game consoles in the early 1990s. Sonic the Hedgehog 3 and Sonic & Knuckles followed in 1994. Sonic 2 continues to receive acclaim, considered one of the greatest video games of all time and one of the best Sonic games. It introduced many elements that became series staples, such as Tails and Sonic's Super transformation. Sonic 2 has been rereleased on various platforms via compilations and emulation, and a remake for iOS and Android devices, developed using the Retro Engine, was released in December 2013. A number of Sonic 2 prototypes have leaked since the game's release; the first, discovered in 1999, played a significant role in the development of the archaeogaming scene.

Gameplay
Sonic the Hedgehog 2 is a side-scrolling platform game. It features a story similar to the first Sonic the Hedgehog (1991): Doctor Robotnik, a mad scientist, seeks the Chaos Emeralds to power his space station, the Death Egg, and traps the animal inhabitants of West Island in aggressive robots. As Sonic the Hedgehog, the player embarks on a journey to collect the Chaos Emeralds and stop Robotnik. The player character can run, jump, crouch, and attack by curling into a ball. Sonic 2 introduces the spin dash, which allows the player to curl while stationary for a speed boost, and Miles "Tails" Prower, a fox with two tails who acts as Sonic's sidekick. By default, the single-player controls both Sonic and Tails simultaneously; a second player can join in at any time and control Tails separately. The player can also choose to play as Sonic or Tails individually.

The game takes place across 10 zones with 23 levels ("acts"). The acts are much larger than the first game's, and the player navigates them at high speeds while jumping between platforms, defeating robot enemies, and avoiding obstacles. Springs, slopes, bottomless pits, and vertical loops populate acts, as do hazards like water and spikes. The player passes checkpoints to save their progress. The last act of each zone ends with a boss battle against Robotnik. The player collects golden rings as a form of health: if the player has at least one ring when they collide with an enemy or obstacle, they will survive, but their rings will scatter and blink before disappearing. The player starts with three lives, which they lose if they are hit without a ring, get crushed, or drown; they receive a game over if they run out of lives. Power-ups like shields and invincibility provide additional layers of protection, and lives are replenished by collecting 100 rings or a 1-up.

If the player passes a checkpoint with 50 or more rings, they can warp to a special stage for an opportunity to collect one of the seven Chaos Emeralds. The player runs through a half-pipe course, collecting rings and dodging bombs. A set amount of rings must be collected to obtain the emerald. If the player collides with a bomb, they lose ten rings and are immobilized momentarily. The stages rise in difficulty and the player cannot enter any stage without passing the previous one. After finishing, the player is transported back to the star post they used to enter, with their ring count reset. When all the Chaos Emeralds have been collected, Sonic can transform into Super Sonic by collecting 50 rings. Super Sonic is invincible, runs faster, and jumps farther, but loses one ring per second and reverts to normal when his rings are depleted.

Sonic 2 introduces a multiplayer game mode where two players compete against each other in a split-screen race in three levels. After one player finishes one of the regular levels, the other player must finish the zone within 60 seconds, or the level ends instantly. In the regular levels, players are ranked in five areas (score, time, rings held at the end of the level, total rings collected, and the number of item boxes broken). The player with wins in the most number of categories wins the level. Players can also compete to obtain the most rings in the special stages.

Knuckles in Sonic 2
Sonic & Knuckles was released in 1994, two years after Sonic 2. The Sonic & Knuckles game cartridge features a "lock-on" adapter that allows players to insert other Sega Genesis cartridges. Attaching Sonic 2 unlocks Knuckles the Echidna in Sonic the Hedgehog 2, a variation of Sonic 2 in which the player controls the Sonic the Hedgehog 3 (1994) character Knuckles the Echidna. The level design is identical, but Knuckles can glide and climb walls, allowing him access to areas inaccessible to Sonic or Tails. However, he cannot jump as high, making some areas, such as certain boss fights, more difficult.

Background
The original Sonic the Hedgehog was developed by Sonic Team in Japan and published by Sega for the Sega Genesis in 1991. The game greatly increased the popularity of the Sega Genesis in North America and is credited with helping Sega gain 65% of the market share against Nintendo, making Sega a formidable competitor. The success meant that a sequel was inevitable.

During the development of Sonic the Hedgehog, Mark Cerny established Sega Technical Institute (STI) in California. Sega wanted to develop more games in America, and Cerny's aim was to establish an elite studio that would combine the design philosophies of American and Japanese developers. STI's first project was Dick Tracy (1991), followed by Kid Chameleon and Greendog: The Beached Surfer Dude! (1992). Shortly after the release of Sonic the Hedgehog, programmer Yuji Naka quit Sega due to disagreements over his salary, dissatisfaction over the time and effort it had taken to finish Sonic, and a lack of support from management. Cerny visited Naka's apartment, listened to the reasons why he left, and convinced him to join STI in America to fix the problems he had had with Sega in Japan. Designer Hirokazu Yasuhara and other members of the Sonic development team joined him, though artist Naoto Ohshima stayed in Japan, where he worked on Sonic CD (1993).

In September 1991, Cerny pitched Sonic the Hedgehog 2 as STI's project for the 1992 Christmas and holiday shopping season—giving the team 11 months of development—but Sega management considered it too soon for a sequel. According to Cerny, this was not uncommon, as marketing executives controlled what games developers created and did not understand game development. STI explored other concepts, but in November, Sega reversed course and told Cerny that it needed Sonic 2 for the 1992 holiday season. Cerny said that this did not create "much of a creative loss", as STI had yet to come up with a game idea on par with Sonic, but lost two months of development. Now with a nine-month schedule, full-scale development started in early 1992.

Team
Sonic 2 development team was much larger than the first game's and consisted of both American and Japanese developers, although the majority of the team was Japanese. Cerny's idea was to have around a dozen of the original game's staff move to STI. Development began with only Americans because the Japanese faced visa problems. According to Cerny, Sega had applied for O-1 expert visas, for "nationally or internationally recognized" people with "a record of extraordinary achievement", unaware that the Japanese developers did not qualify. Sega's Masaharu Yoshii was credited as director, though he did not join until halfway through development. According to Yoshii, he became involved after Cerny quit and he was installed as the head of STI. However, Cerny said that he left just as development concluded.

The development was complicated by the cultural and language barriers between the Japanese and American developers. The Japanese were used to crunch conditions, with Cerny noting they often worked through the night and slept in their cubicles. In contrast, the Americans locked the STI offices at night. Cerny had envisioned the Japanese acting as mentors to the Americans, but cooperation was difficult since the Americans could not speak Japanese. Level artist Craig Stitt recalled Yasuhara as easy to work with, but Naka as "an arrogant a pain in the ass" not interested in working with Americans. Artist Tim Skelly said that Naka would have been happier working with an all-Japanese team.

Yasuhara said meshing the Americans' art with art by lead artist Yasushi Yamaguchi was the largest hurdle. Yamaguchi had to check the teams' enemy and stage designs while producing his own. While Yamaguchi was assisted by Jina Ishiwatari, he worked mostly alone. Stitt called Yamaguchi "a machine" who worked long hours and reworked other artists' levels repeatedly to ensure quality. For example, Stitt felt disappointed when Yamaguchi redid his background art for the Oil Ocean level, but did not argue because he was not satisfied with the original background and Yamaguchi's was much better. Naka and Yasuhara also occasionally checked the art, with Skelly noting Naka was quite particular. The title screen and Casino Night level art were both completely reworked shortly before release.

Sonic 2 did not become playable from start to finish until the last 48 hours of development, in September 1992. The team planned to use a 4MB cartridge, the same cartridge size as the first game, but STI ran out of space towards the end of development. To make sure the game would be finished in time for Thanksgiving, Yoshii went to the Japanese side of Sega for help. Managing director Daizaburou Sakurai contacted Sega Enterprises president Hayao Nakayama, who allowed the team to double the ROM size to avoid a delay. Yoshii said that Sonic 2 would not have been ready for release without Sega of America's bug-checking process. Around 50 developers worked as bug checkers, and the process took two to three weeks. When Sonic 2 was shipped to Japan for production, copies of the source code were sent on separate planes to ensure that the game would arrive in case of an accident.

Art and design


Sega of America marketing director Al Nilsen said that STI wanted "to go all out" to ensure Sonic 2 would be as successful as the original Sonic, since sequels were generally not well regarded. STI began with various ideas about how to improve the first game's formula, beginning with making Sonic faster. In the first game, Sonic was restricted by a speed cap well below his maximum possible speed; STI lifted the cap for Sonic 2. This led to the conception of the spin dash, which removed the need to backtrack for momentum. Early in development, STI implemented a routine whereby Sonic was hurt if he ran into a wall at full speed, but this was removed in later builds.

Yasuhara had ambitious plans Sonic 2, and designed it with "'blue sky' ideas". Assuming STI had two years of development, he conceived a plot in which Robotnik took over the world and Sonic used time travel to stop him. The plot was scrapped, but many of Sonic 2 levels were taken from it; for example, Hill Top Zone (which features dinosaur enemies) was intended to be a past version of Green Hill Zone, while Chemical Plant and Casino Night came from the Robotnik-ruled future. Sonic CD time travel feature was coincidental, and differed from Sonic 2 as it implemented it as a game mechanic rather than merely a story feature.

Sonic 2 features twice as many unique level tropes compared to the first game, and STI chose to have most levels end after two acts rather than three. According to Stitt, level development began when artists were given a paper map with ideas regarding the level theme. Once the design was settled, the artist would then draw the art pixel by pixel and then input the graphics in the game itself. The graphics and animations were implemented using the Digitizer, Sega's proprietary graphics system for the Genesis. The artists had to deal with palette limitations, as only 64 colors could be displayed on-screen. Yasuhara was inspired to design Casino Night because he noticed that Sonic springs felt similar to the gimmicks of pinball tables, while Sky Chase—which features Sonic riding a biplane as he attempts to reach Robotnik's base—was inspired by Hayao Miyazaki's anime Future Boy Conan (1978). Cerny's job was to oversee the level design and gameplay, and also acted as an art director.

Yasuhara wanted to add a second playable character so siblings could play together. An internal contest was held to determine the new character; the winning design was Yamaguchi's twin-tailed fox, inspired by Japanese folklore about the kitsune. Sega of America objected to the character's name, Miles Prower (a pun on "miles per hour"), so he was given the nickname Tails as a compromise. Tails was implemented using an artificial intelligence routine that allowed him to mimic Sonic's movements, becoming playable with a second controller. Tails was also used in the multiplayer mode, something that Naka had attempted to implement late in development of the original Sonic. He implemented it in Sonic 2 by using the Genesis' rarely-used interlaced mode to create split-screen gameplay.

Skelly designed the appearance of the pseudo-3D special stages, based on a tech demo created by Naka. The special stages were created from pre-rendered 3D polygons, video of which was compressed and halved vertically and horizontally to fit in the game cartridge. According to Cerny, the 3D look was born out of the sentiment that the special stages needed to look "flashy". Skelly said that the idea came from STI programmer Steve Woita, who "recalled an interesting scheme that allowed us to do bit-map graphics with a character-stamp based system". Graphics for rings, bombs, and characters were provided by Yamaguchi, while the stages were designed by Shinobi (1987) director Yutaka Sugano. In retrospect, Cerny felt the stages, while visually impressive, did not have as much gameplay depth as the special stages of the original Sonic, which featured Sonic navigating a rotating maze.

Cut content
A large amount of content was cut. Nilsen said Sonic 2 "probably could have been three times the size if we left in everything that was there. Naka and team really did a phenomenal job of editing what was going to be in the game, and weren't afraid to say, 'I've been working on this for four months, it's not working. Let's take it out.'" One scrapped stage, Hidden Palace Zone, featured extensively in prerelease advertisements. It was planned as a secret stage accessed by collecting Chaos Emeralds; according to Naka, it would explain the origin of the Chaos Emeralds and grant Sonic his Super Sonic powers. Though Hidden Palace was one of the first levels implemented, work on it stopped in mid-1992, and it was removed shortly before completion for a lack of time and cartridge space. Stitt, who created the Hidden Palace art and considered its foreground among his favorite work, was angry when he learned it was cut.

Other cut levels included a forest level, which was implemented but hardly worked on, and a desert level. One scrapped level, Genocide City, was renamed Cyber City because the Japanese developers had not understood the negative connotations of the word genocide. Its level layout was used in the Metropolis Zone level. Sega of America CEO Tom Kalinske, product manager Madeline Schroeder, and Nilsen worked closely with STI; Nilsen said the feedback loop helped the team determine what needed to be cut. Most cuts were made to the Americans' designs, and many Americans were furious when they learned their work had been cut. Stitt said that he may have been the only American whose art was used in the final game. According to Yasuhara, most level cuts were due to time constraints and he had been upset by each of them. In 2017, he said he wanted to remake Sonic 2 with the cut content restored.

Music
As with the first game, the Sonic 2 soundtrack was composed by Dreams Come True bassist and songwriter Masato Nakamura. According to Yamaguchi, a Sega of America employee asked STI to use music composed in-house instead; the team felt team the music was "awful" and refused to use it, so Sega rehired Nakamura. Nakamura had become famous in Japan after the release of Sonic the Hedgehog, and increased his asking price considerably. As with the first game, Nakamura began composing early in development with only concept art for reference. He treated Sonic 2 like a film and attempted to reflect the atmosphere he felt in the concept art. Nakamura composed Sonic 2 simultaneously with the Dreams Come True album The Swinging Star (1992); as a gift to the developers, he produced an alternate version of the Sonic 2 ending theme, "Sweet Sweet Sweet", for the album.

Since Sonic 2 was more technically advanced than its predecessor, Nakamura "wanted to create music that showed progress... It was like the Indiana Jones sequels. Same concept, but with more fun and excitement." Nakamura said that he felt considerable pressure, as he understood that expectations were high due to the first game's success. STI let Nakamura "do as [he] pleased", which he felt allowed him to create "such melodic tunes and unusual rhythm patterns". He composed using a Roland MC-4 Microcomposer; he noted that it was challenging due to the Genesis' limited sound capabilities, but the limitations encouraged him to be more inventive. Five or six individuals worked to convert Nakamura's music to the Genesis hardware for use in the game.

Release
Sega aggressively promoted Sonic the Hedgehog 2, spending approximately $10 million on its advertising campaign. Sega's marketing team was confident that the game would be a major success and, as Brian Shea of Game Informer wrote, sought to make the release "as much a celebration as it was a product launch." Promotion began in early 1992, when Sega sent mockup screenshots to magazines. Sega then sent an early build to be featured on Nickelodeon's Nick Arcade (1992) children's game show. The build was featured several times on the program, notably in a competition between Clarissa Explains It All (1991–1994) stars Melissa Joan Hart and Jason Zimbler; Hart "memorably" struggled to play it. Sega gave away T-shirts as preorder gifts and sent stores dry-erase boards to count down the days to release. Teaser posters bore the slogan "Are You Up 2 It?".

Sega sought a global release date to make Sonic 2 available in all stores on the same day, a novel concept at the time. This required Sega to reconfigure its distribution system to ensure that games were available in all major stores. The release date in North America and Europe, Tuesday, November 24, 1992, was marketed as "Sonic 2sday". In Japan, the game was released three days earlier, on November 21. Sega of America collaborated with Emery Worldwide to produce stickers celebrating "The Great Sonic 2 Shipment", and 50 people dressed as Sonic greeted the three planes carrying copies of Sonic 2 at Heathrow Airport. Sega considered shipping the cartridges with holographic label, but did not as such labels would have been prohibitively expensive. Initial copies of Sonic 2 shipped with several bugs; later copies used a build STI made a few days after completing the game. The cover art, featuring Robotnik "leering over a checkered '2'" behind Sonic and Tails, was illustrated by Greg Martin.

An alternate version of Sonic the Hedgehog 2 was developed by Aspect Co. for Sega's 8-bit consoles, the Master System and the handheld Game Gear. The 8-bit version of Sonic 2 features different level designs and music, as well as a different plot in which Sonic must rescue a kidnapped Tails. It was later included in Sonic compilations, such as Sonic Adventure DX (2003) for the GameCube and Windows and Sonic Gems Collection (2005) for the GameCube and PlayStation 2.

Sales
Sonic 2 broke video game sales records and became the fastest-selling game at the time. In the US, it sold 600,000 copies within a day in addition to 400,000 preorders. In the UK, it sold 750,000 copies within a week, accounting for 48% of all UK software. It was the top-seller on Gallup's Sega charts for the UK, Japan, and the US for months. Sonic 2 grossed US$450 million in 1992 (US$million adjusted for inflation), and its release-day revenue exceeded the total revenue that the bestselling rock music CD of 1992, Simply Red's Stars, had earned throughout the year. Sonic 2 sold six million copies worldwide by August 2006, making it the second-bestselling Genesis game behind the original Sonic the Hedgehog.

Reception
Sonic the Hedgehog 2 received acclaim, with many critics considering it better than the first Sonic. Electronic Gaming Monthly (EGM) wrote that Sonic 2 was a game "that can best be described with a lot of 2s", being twice as long and fun as its predecessor. Comparisons between the two games were common; many reviewers noted Sonic 2 was quite similar to Sonic the Hedgehog in appearance and gameplay. The similarities did not bother Electronic Games, which said the level variety and multiplayer made it an improvement, but Mega and GamesMaster considered them a detriment. In particular, GamesMaster felt that Sonic 2 was just more of Sonic the Hedgehog and did not improve much.

Critics commended the presentation, with EGM describing Sonic 2 as an impressive showcase of the Genesis hardware. The visuals were praised as colorful and detailed, and EGM and Mega highlighted the backgrounds for their intricacy. GamePro, Mean Machines Sega, and Mega wrote that the updated sprites were larger and animated better; Mean Machines said Sonic's new animation frames made for a smoother appearance. Several critics said the graphics were better than the first game's, though Computer and Video Games (CVG) and GamesMaster felt they were about the same. CVG said this was not a problem since Sonic graphics were already excellent. The music was also praised, though CVG and GamePro respectively said it was not as memorable as the first game's or as impressive as the visuals.

The level design and gameplay were praised. Critics said Sonic 2 levels were larger and featured more variety than the first game, which CVG and GamePro wrote incentivized exploration and replayability. Mean Machines and Mega said it was clear that Sega sought to address the criticisms levied against the first game regarding its length and low difficulty, though Sonic 2 easiness was still criticized. Mega and GamesMaster wrote that despite Sonic 2 larger size, it could still be completed fairly quickly, and one of GamesMaster reviewers said they finished it in one sitting without receiving a single game over. CVG said the difficulty was Sonic 2 only major problem, but GamePro and Mega said the difficulty was remedied by the replay value that the levels' branching paths and various secrets provided. Critics considered the special stages a highlight, GamePro writing they challenged the Genesis' theoretical inability of scaling, though Mega felt they lacked the skill curve of the first game's.

Reviewers considered the multiplayer mode one of Sonic 2 best additions, though some disliked the split-screen effect. Mega said that the ability to race against a friend rather than just the in-game timer added substantial depth, and EGM said it would double the amount of fun players would have. Multiple critics praised Tails, with GamePro calling him "about the cutest companion that any Sonic fan could ask for". Conversely, GamesMaster said Tails was briefly fun but ultimately little more than a sprite-swapped Sonic.

Accolades
Sonic 2 received numerous year-end accolades and nominations. It received the Golden Joystick Awards for Best Original Console Game and Promotional Campaign of the Year, and was a runner-up for the Chicago Tribune Best Game of the Year award after The Legend of Zelda: A Link to the Past (1991) and the console version of Street Fighter II (1992). EGM named it the best Genesis game of 1992. At Electronic Games' Electronic Gaming Awards, it won Best Electronic Game Graphics, while losing the Video Game of the Year award to Street Fighter II.

Aftermath
For all its success, Sonic 2 took a toll on STI. Naka refused to develop another Sonic game if he had to work with the Americans again. When Atari veteran Roger Hector became the division's head, STI split into two teams: the Japanese developers led by Naka, and the American developers. The Japanese team started working on a sequel—later split into two games, Sonic the Hedgehog 3 and Sonic & Knuckles—in January 1993; it was conceived as an isometric game that used the Sega Virtua Processor chip, but was retooled to reuse the Sonic 2 engine after it became apparent that the chip would not be finished in time. Many of Sonic 2 unused concepts were incorporated in Sonic 3 and Sonic & Knuckles, including the Hidden Palace level. Like their predecessors, Sonic 3 and Sonic & Knuckles were critical and commercial successes when they were released in 1994.

As the Japanese worked on Sonic 3, the American team developed the spin-off Sonic Spinball (1993), a pinball game commissioned after Sega's research determined that Casino Night Zone was one of the most popular levels in Sonic 2. Following the completion of Sonic & Knuckles, Yasuhara quit, citing differences with Naka, and went on to develop games for Sega of America. Naka returned to Japan with developer Takashi Iizuka to work with Sonic Team, and was reunited with Ohshima. A concept developed during Sonic 2 production formed the basis of Naka, Iizuka, and Ohshima's Sega Saturn game Nights into Dreams (1996). The American team developed Comix Zone (1995), The Ooze (1995), Die Hard Arcade (1996) with Sega AM1, and the canceled Sonic X-treme before STI was disbanded in late 1996 as a result of changes in management at Sega of America. Meanwhile, Cerny began collaborating with Sony Interactive Entertainment and helped create the PlayStation franchises Crash Bandicoot and Spyro the Dragon.

Rereleases
Sonic 2 has been ported to multiple platforms. In 1993, Sega released a version for arcade cabinets using its Sega Mega Play arcade system board. A Sega Saturn port included in the compilation Sonic Jam (1997) introduces an alternate difficulty mode that alters stage layouts and removes some levels for an easier experience. Other compilations featuring the game include Sonic Classics 3 in 1 (1995) for the Genesis; Sonic Mega Collection (2002) for the GameCube, PlayStation 2, and Xbox; Sega Genesis Collection (2006) for the PlayStation 2 and PlayStation Portable; Sonic's Ultimate Genesis Collection (2009) for the Xbox 360 and PlayStation 3; Sonic Classic Collection (2010) for the Nintendo DS; and Sega Genesis Classics (2018) for the Nintendo Switch, PlayStation 4, and Xbox One. Jam, Mega Collection, and Classic Collection include Knuckles in Sonic 2 as a bonus.

A remake of Sonic 2 was released for Android and iOS devices on December 12, 2013, and for Apple TV on March 24, 2016. The remake was developed from scratch by Christian "Taxman" Whitehead and Simon "Stealth" Thomley using the Retro Engine, previously used in Whitehead's 2011 Sonic CD remake. The remake adds enhancements such as support for widescreen displays, Knuckles as a playable character, time and boss attack modes, online multiplayer, additional multiplayer stages, and Tails's flying and swimming abilities from Sonic the Hedgehog 3 (1994). It also restores Hidden Palace Zone as an optional, secret level. Whitehead redesigned Hidden Palace with input from Sonic Team, which informed him that STI had been dissatisfied with the original level design.

A Nintendo 3DS port was developed by M2 and released as part of Sega's 3D Classics line in Japan on July 22, 2015, and elsewhere on October 8. The port features stereoscopic 3D visuals, the option to switch between the game's regional variants, alternate sound and visual modes, and cheats. M2 was originally hesitant to port the game, and it took the most effort of the 3D Classics line due to its large size and elaborate levels. Several technical tricks, such as the interlacing in the multiplayer mode and the pre-rendering in the special stages, had to be reprogrammed so they could be retained. M2 also developed a Nintendo Switch port for the Sega Ages line, released in February 2020. It includes most of the additions from the 3DS version, as well as the option to use Sonic's Drop Dash ability from Sonic Mania (2017), a time attack mode, and Knuckles in Sonic 2.

Sonic 2 has also been rereleased on digital distribution platforms. It was was made available for download on the Wii's Virtual Console on June 11, 2007, the Xbox 360's Xbox Live Arcade on September 12, 2007, the PlayStation 3's PlayStation Network on April 19, 2011, Steam on January 26, 2011, and for Nintendo Switch Online's "Expansion Pack" subscribers on October 25, 2021. These versions run via Genesis emulation, and the Wii and Xbox 360 versions allow users to play Knuckles in Sonic 2 if they also own Sonic & Knuckles. An emulated version for iOS was released in April 2010, but was replaced by the remake in 2013; those who had purchased the original version were offered the remake as a free update.

Retrospective reception
Sonic 2 continues to receive acclaim. Critics consider it an improvement over the first Sonic the Hedgehog, saying it features greater level diversity and design, better graphics, and quality-of-life improvements. GameSpot said that Sonic 2 "does everything a sequel is supposed to do. It resolves many of the first game's shortcomings and incorporates a slew of minor upgrades that cumulatively amount to a fresh experience." Critics felt the emulated downloadable rereleases were easy to recommend. TeamXbox, Eurogamer, and Hardcore Gamer said the level design, music, and fast gameplay still hold up exceptionally well,  and GamesRadar+ called it "the most user-friendly of all the Sonic games, beautifully presented and still a challenge if you want to complete it properly."

Retrospective objects of criticism include the multiplayer mode and the implementation of Tails. Reviewers disliked the image distortion brought about by the multiplayer mode's squeezed and flickering graphics, while they considered Tails a burden due to his interference in boss battles. Additionally, Eurogamer described the visuals of the special stages as "dreadfully blocky", and IGN felt that the inclusion of Tails in the stages was "detrimental at best" since he constantly hits bombs and makes the player lose progress. Some critics wrote that the late-game stages were difficult and complex, while GamesRadar+ said that "[the game] could be criticized for 'playing itself'" during sequences when Sonic careens at high speeds.

The 2010 iOS and DS versions received middling reviews, with criticism for their quality and lack of multiplayer,  but the 2013 remake was considered the definitive version. TouchArcade called it a "beautiful remaster" that would appeal to old and new fans and found it surreal to finally play the once-removed Hidden Palace in an official capacity. Critics praised the 3DS version for its implementation of the system's stereoscopic 3D and the added bonus features, with Nintendo World Report writing that the addition of cheats made difficult moments less frustrating. Nintendo Life was disappointed that the Switch version did not include the 2013 remake's features and felt that M2 should have chosen a lesser-known game to port, given the copious number of Sonic 2 rereleases. Nonetheless, Nintendo Life felt it was an excellent port and a "must-have" for first-time players.

Sonic 2 is frequently cited as one of the greatest video games of all time. Listing the game at number 71 in its Top 100 Games of All Time list in 2001, Game Informer wrote that Sonic 2 was "the most challenging and finely polished Sonic the Hedgehog title." Sonic 2 took first place in a survey conducted by Official Nintendo Magazine to determine the fan-favorite Sonic game in 2010, and GameZone named it the second-best Sonic game (behind Sonic 3) in 2011. GamesRadar+ named Sonic 2 the best Sonic game and the second-best Genesis game of all time (behind Streets of Rage 2 (1992)) in 2017. In November 2017, Sonic Team head Takashi Iizuka said that he felt Sonic 2 "really is the best of the classic Sonic series. The level design is just really, really solid... all of the [Sega] staff would say it was a great game for Japanese tastes but also a great game for American tastes. Sonic 2 really captured that global sense of game design and level design."

Influence
Sonic 2 was a major factor in keeping Sega competitive during the console wars of the fourth generation of video game consoles in the early 1990s. It boosted Genesis sales enough to solidify Sega as Nintendo's near-equal and cemented Sonic as a video game mascot on par with Nintendo's Mario. Sonic 2 is credited for originating the concept of a concrete worldwide release date. The practice was unheard of before Sonic 2 release and became a widespread industry trend in the following years.

Sonic 2 introduced many elements that defined the Sonic franchise. The spin dash ability became a series staple, and Tails appeared in nearly every subsequent Sonic game and starred in two spin-offs, Tails Adventure and Tails' Skypatrol, for the Game Gear in 1995. For the franchise's 20th anniversary in 2011, Sega released Sonic Generations, which features reimagined versions of stages from across the series' history. The PlayStation 3, Xbox 360, and Windows versions contain remakes of Sonic 2 Chemical Plant Zone and the Death Egg Robot boss fight, while the Nintendo 3DS version contains a remake of Casino Night. Additionally, a Casino Night-themed pinball minigame was released as downloadable content. Sonic Mania features reimagined versions of Chemical Plant and Oil Ocean, while Sonic Forces (2017) features a reimagined version of Chemical Plant. The Death Egg Robot appears in the 2022 Sonic the Hedgehog 2 film, while one of its posters recreates Martin's Sonic 2 box art illustration.

In the years since Sonic 2 release, a number of prototypes have been leaked online. In 1999, Sonic fan Simon Wai discovered an early prototype containing the scrapped Hidden Palace, Wood, and Genocide City levels on a Chinese website and shared it with the Western Sonic fandom. The discovery played a significant role in the development of the video game preservation scene, as it encouraged players to datamine games and document prototype ROM images so they could understand how popular games were developed. Journalist Heidi Kemps presented the prototype to Naka during a 2005 GameSpy interview and he identified it as originating from a preview cartridge that had been stolen from a 1992 New York City toy show. A Sonic fan discovered the Sonic 2 prototype featured on Nick Arcade in 2006 and raised over US$1,500 to buy the cartridge and release the ROM image online. The Nick Arcade prototype, while primitive and unpolished, showed fans how STI built the game atop the original Sonic the Hedgehog.

A high-definition (HD) fangame remake, Sonic 2 HD, entered development for Windows and macOS in 2008. The project was canceled in 2012 after the release of a game demo that Retro Gamer staff described as "blighted by programming incompetence", due to high system requirements and digital rights management that inadvertently triggered antivirus software. However, the project was restarted by a new team in 2014. It is planned to feature additional levels, multiplayer modes, and the option to play as Knuckles. Sonic 2 has also been noted for its active modding scene that releases ROM hacks featuring new game mechanics and playable characters. Modders decompiled the source code of the 2013 Sonic 2 remake in 2021, allowing it to be unofficially ported to any platform.