Sonic the Hedgehog refers to the Sonic the Hedgehog video game series released by Sega, and starring its eponymous mascot, the video game character Sonic the Hedgehog. The video game series is the primary product in a multimedia franchise, including products in a wide range of media.

Sonic: The One Ring is a hack of the original Sonic the Hedgehog game for the Sega Mega Drive / Genesis, created by Mercury. Its defining (and titular) feature is that in each Act, all rings but one have been removed, and Sonic cannot complete the Act without this One Ring in his possession. Thus, in each Act, Sonic must search for the One Ring that will afford him the opportunity to progress. Several alterations have been made to the game, to somewhat balance the lack of rings, and allow backtracking during the search.

Sonic the Hedgehog 2 (ソニック・ザ・ヘッジホッグ2 Sonikku za Hejjihoggu Tsū?) is a platform video game developed by Sonic Team and Sega Technical Institute, and published by Sega. The game is an installment in the Sonic the Hedgehog series, and focuses on the protagonist Sonic the Hedgehog and his friend, a fox named Miles "Tails" Prower,[3] who must stop the series antagonist Dr. Ivo Robotnik from stealing the Chaos Emeralds to power his Death Egg space station.Originally released for the Sega Genesis/Mega Drive in 1992, the game was a critical and commercial success, with critics praising it for building upon the original Sonic the Hedgehog game. The game has sold over 6 million copies, making it the second-best-selling game on the console, behind only its predecessor in the Sonic series. Since its initial release, the game has been released in several compilations and download releases for various platforms, which were also generally positively received.

Sonic 2 Long Version (which is released alongside Sonic 2 & Knuckles Long Version) is a more complete version of Sonic 2, which makes it somewhat similar to Sonic 2 Delta. This hack features four levels originally scrapped during Sonic 2's development. No levels have been changed, only added. This hack was written in hex, without the aid of any special hacking programs, because the creator uses a Mac, and no hacking tools had been released on that platform at the time of development.