Sonic the Hedgehog (1991) prototype discovered

Determined to start 2021 off on the right foot; infamous scene member 'drx', along with The Cutting Room Floor have uncovered what is long thought to have been lost to the ages.

While a number of Sonic the Hedgehog 2 (1992) betas and prototypes, including the famous Nick Arcade build have been floating around the internet since 2006; and then more recently in 2019 we saw the surprise discovery of a Sonic the Hedgehog 3 (1994) prototype - it's long been thought that any and all early builds of Sonic's first outing on SEGA's 16-bit machine would never be found.

Although plenty of early show floor demos and VHS tapes have made their way onto the internet which show glimpses of early Sonic 1 footage and a bevy of fan made hoax ROMs exist - until last night this is all we had to show for SEGA's first entry in the Sonic the Hedgehog series.


That was until last night, when during their last Twitch stream of 2020, The Hidden Palace Zone closed off their stream with a surprise showing - an early prototype build of Sonic the Hedgehog for the SEGA Mega Drive / Genesis.

Sonic_the_Hedgehog_(16-bit)_(Prototype)_(2).png Sonic_the_Hedgehog_(16-bit)_(Prototype)_(7).png Sonic_the_Hedgehog_(16-bit)_(Prototype)_(18).png Sonic_the_Hedgehog_(16-bit)_(Prototype)_(31).png Sonic_the_Hedgehog_(16-bit)_(Prototype)_(36).png Sonic_the_Hedgehog_(16-bit)_(Prototype)_(57).png Sonic_the_Hedgehog_(16-bit)_(Prototype)_(61).png

Although an exact build date of the ROM is unknown, it's thought to be from mid to late development of the title. A number of zones are near complete while a couple including Labyrinth and Spring Yard Zone look quite different from the final product.

Here is a list of key differences that has been compiled by members of the scene:
  • Normal SEGA startup - no SEGA choir
  • No 'Sonic Team Presents' screen
  • Many level layout differences
  • Many level art differences
  • Object placement differences
  • Large rolling ball in GHZ
  • LZ is missing water entirely
  • UFO's present in MZ sky
  • Slower lava in MZ
  • Missing boss in MZ
  • Some instrumentation differences
  • Special stage ring does not appear at end of the level
  • Spring Yard Zone is known as Sparkling Zone
  • Star Light Zone is very unfinished
  • Scrap Brain Zone shows as Clock Ork Zone
  • COZ is very unfinished
  • Splats (enemy) is present and functional via debug

More detailed information on this release as well as a download can be found via the link at The Hidden Palace Zone below.

Maybe some day we'll also get to see the incredibly rare Tokyo Toy Show prototype/proof of concept version of Sonic 1?

:arrow: Twitch stream (starts at approx 40:00)
:arrow: The Hidden Palace Zone


Well-Known Member
Jun 12, 2009

It's funny making Sonic jump like he's Mario at the end of levels like he's Mario and Splats jumping through the moving floor into a pit of lava.


Your Local Random Internet Geek
Jul 14, 2018


Editorial Team
Nov 21, 2005
United Kingdom
Can someone pls tell me what's so special about this?
The opening post covers some of the differences between this and the final released version.

Generally though Sonic (a fairly important computer game in the history of such things) did not spring fully formed onto the world. Various demo builds, magazine screenshots, video and whatnot were released during development that did not make the final cut (sometimes for gameplay, sometimes for budget, sometimes for other reasons).
However between said screenshots, the stuff left behind in various versions of the ROM* and leaked code in various forms over the years then hackers have managed to piece together and remake bits of it for this and its sequel (Sonic 2 on the megadrive probably being one of the more extensively contemplated games out there for this sort of thing -- Resident Evil probably being the only franchise to stand a chance of having had as much attention and those guys are crazy, guy on the previous link also having something of a playlist of Resident Evil related things if you are interested in the stuff they went in for). If indeed the list of changes above is what it is then it also provides something of an insight into how the game was designed which is also of interest to many; if an idea was added later in development but went on to become a key feature then that is valuable info, and this being the first then features later dropped could also be a thing. In some games it can also show how the devs wanted it to be before the publisher wandered in and said it must be playable by quadriplegic and comatose 4 year olds, had to play to regional censors ( ), or indeed this being the 8-16 bit era then the pubs wandering in and saying "the kids like hard games and we don't want them to rent it/trade it in after 2 weeks" make it so.

*prior to the PS1 most console games were written in assembly. This means if you deleted a bunch of stuff you could not just recompile and go from there with the old stuff now gone. To that end devs would often just note the sections in question as being effectively blank space, try to make sure there was no way to access them during normal play and leave the data there.
Those being three of the better known sites dedicated to finding and archiving such things, the former not caring so much for things from magazines and videos and instead being more about actual code. Most ROM hacking websites (which includes this place and linked above for a patch) are also not averse to playing around with such things.

Anyway hope that serves as a brief intro to why game prototypes, betas and information thereon is often sought, examined and shared onwards.
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