Bad Export for You: Like most early Mega Drive and Master System titles, the European version lacks refinement to work on 50 FPS PAL televisions, resulting in the PAL version becoming far slower and more sluggish compared to the NTSC-J version. Even the music plays slower for both versions, an issue that was at least fixed for all later Sonic titles, and some re-releases of this title such as Sonic Jam and the Sega Ages package.
Breakthrough Hit: This was the game that put Sega on the map as a console gaming company and Sonic Team as a premier development team.
Dueling Works: Sonic managed to go toe-to-toe with Super Mario World, selling roughly the same number of copies, even though Mario was more popular on the other side of the Pacific.
Dummied Out: There are several things that were meant to appear in the original version of the game. These elements were later included in the Debug Mode for the 2013 remaster:
A boulder chase in Green Hill Zone. In the final version, the boulder sprites were only used for Robotnik's wrecking ball contraption.
Swimming goggles for the Labyrinth and Scrap Brain Zones.
First Appearance: Of Sonic, of course,note though Sonic did make an Early-Bird Cameo as an air freshener in Rad Mobile, which was released in arcades several months before the game’s release but also of Doctor Eggman/Robotnik, the little animals rescued by Sonic (with the exception of Flicky, who previously appeared in the game of the same name), and various Badniks such as Crabmeats and Buzz Bombers.
Killer App: This was the game to own on the Genesis, and the one that would turn Sega into a force of nature in the video game industry. The ultimately superfluous "Blast Processing" phrase was used to advertise the Genesis to hype up this game's status as such. It also came pre-installed in ROM in some versions of the Sega Master System.
Mid-Development Genre Shift: The initial concept was a more traditional platformer with puzzles and exploration akin to Super Mario Bros. 2. The final product, while still a platformer, focused more dominantly on its now trademark speed. This evolution is even more prominent in its sequel.
Missing Episode: The Tokyo Toy Show build (named after the fact that it was shown at the 1990 Tokyo Toy Show) is famous for being the first formal reveal of the game to the public and for being remarkably different from the final game. Unfortunately though, for unknown reasons, the build would disappear afterwards and become lost to time, with screenshots from back in the day being the only proof behind the build's existence. Not even Sega or Sonic Team are sure what happened to it, as they planned on including the build in Sonic Mega Collection, only to not find any traces of the build in their archives.
No Port For You: The 2013 remake was initially exclusive to iOS and Android, despite the fact that the last time Christian Whitehead made a remake of an older Sonic game, it was ported to consoles as well as PC. Sonic 2 also has this problem. However, a fan decompilation exists that allows the 2013 remakes of this game and its sequel to be played on PC. The project is also open source and instructions are provided to bring the mobile port onto other platforms such as the Xbox One, PlayStation Vita, and Nintendo Switch. Later on, Sonic Origins would officially bring the two games to consoles and PC.
Pop-Culture Urban Legends: A widely-circulated factoid says that the "Sega scream" takes up 1/8 of the 512KB ROM space on the cartridge, or about 64KB (12.5%). In actuality, it takes up about 26KB, or 1/16 (5.15%) of the ROM.
Port Overdosed: Over the years, this game has been made available for:
Three separate multi-game cartridges on the Genesis.
The Genesis and Game Gear versions include their final bosses as unlockable extras in Sonic Gems Collection for the Nintendo GameCube and PlayStation 2.note With the full games playable via cheat devices.
Sega Mega Drive/Genesis Collection for the PlayStation 2 and PlayStation Portable.
Via digital download on Xbox Live (by Digital Eclipse), PlayStation Network (also by Digital Eclipse), Virtual Console, various Android and iOS devices (initially by Sega, later updated by Christian Whitehead and Simon Thomley to include continues).
The Christian Whitehead and Simon Thomley ports were re-released as part of Sonic Origins along with CD, 2, and 3&K for the PlayStation 4, PlayStation 5, Xbox One, Xbox Series X|S, Nintendo Switch, and Steam. The following year, Sonic Origins received a Plus expansion that also bundles the entire Sonic the Hedgehog Game Gear library.
Due to video game release dates not being standardized at the time, nobody knows exactly when Sonic the Hedgehog was first released in North America. Sega considers June 23, 1991 to be the official North American release date (as reflected by Sonic Jam, which Sonic Adventure 2 and Sonic Origins based their Meaningful Release Date on), but some sources dispute this, with one retailer listing in American newspapers◊, a number of Usenet posts about having obtained the game and a physical receipt pointing towards the game having been out on shelves earlier in the month. An attempt has been made to clarify this situation, with limited success.
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