Sonic the Hedgehog 2 (Simon Wai prototype)

The Simon Wai prototype (sometimes erroneously referred to as Sonic 2 Beta) refers to an early build of Sonic the Hedgehog 2 for the Sega Genesis; it is named after the person who discovered it, Simon Wai, who released the ROM onto the Western internet in early 1999. The ROM image is believed to have been compiled in early August 1992 due to another build, one dated August 21, 1992 also being leaked, and having many similarities.

The prototype is considered a major event in the history of video games; many attributed it for sparking interest in prototype preservation and is well known for the amount of differences compared to the final; it is also among the most pirated video games in history, with a majority of Sonic 2 bootleg carts containing it.

Development of Sonic the Hedgehog 2
Sonic the Hedgehog 2 is a 1992 platforming video game developed by Sega Technical Institute and published by Sega; development for the game began in November 1991 with a staff consisting of Americans and Japanaese. Programmer Yuji Naka returned for the sequel, having left Sega of Japan in 1991 due to disputes about proper credits, before being hired by Sega of America; Hirokazu Yasuhara also returned, while Sonic's original character designer Naoto Ohshima stayed in Japan to develop Sonic the Hedgehog CD.

During development a huge portion of content was cut from the game due to time constraints; most infamously, Hidden Palace Zone, which was meant to be accessed upon collecting all seven Chaos Emeralds and, upon completion, would allow the player to transform super; reasons for its removal are time constraints and the developers not liking its layout. Among other plans scrapped were time travel, which was dropped immediately but recycled for Sonic CD, and several badniks.

Release
On November 16, 1998, a person by the name of Simon Wai was searching around on the Chinese Geocities site when he clicked on a link that downloaded him a file titled MD8123.smd; upon playing it, he realized it was a version of Sonic 2 that shared lots of similarities to what was seen in magazines prior. Early in 1999, Simon Wai would launch The Sonic 2 Beta Page in order to document his findings; upon the ROM's release it quickly spread around the internet due to its large amount of differences from the final.

In a 2005 interview with GameSpy, Yuji Naka stated that this particular prototype was meant for a 1992 toy show in New York where they would show off four stages; however the cartridge used had apparently been stolen prior to the intended debut. After the theft, Sega changed their guidelines about previews requiring that representatives from Sega be present to prevent a similar theft from occurring.

Legacy
In Novemeber 2006, popular prototype preservation site Hidden Palace released a build of the game that was used on the Nick Arcade show; this build was found to have been earlier than the Simon Wai build and has various leftovers from Sonic 1. During the February 27, 2008 prototype dump, seven late betas dated from September 18 to September 24 were also discovered. Another late beta, which was leaked around November 1992 was also dumped in 2019, followed by a build dated August 21, and another dated September 14 (titled "pre-beta").