Prerelease:Sonic the Hedgehog (Genesis)/1990 Tokyo Toy Show
This is a sub-page of Prerelease:Sonic the Hedgehog (Genesis).
The debut of Sonic the Hedgehog occurred at the Tokyo Toy Show in June 1990, a full year before its eventual release. Only screenshots and off-screen photos remain of this build, with most context derived from vintage magazine coverage and developer interviews.
History
Info about this build has always been scarce and difficult to verify. In addition, Yuji Naka (the game's lead programmer) has privately and publicly disputed two key details about this demo that are supported by the historical record: whether or not it was available to the public on the show floor, and whether or not it was playable.
- The History of Sonic the Hedgehog (an official retrospective published by Sega in 2013) states that, while the demo did indeed appear at TTS '90, it was only shown behind closed doors to industry insiders and was not publicly shown on the convention floor.
- Naka contradicts this claim, stating in a Twitter/X private message that the demo was indeed present at the Sega booth during TTS '90.
The demo can be seen running in two photos of Sega's booth at the toy show, and its screening can be seen (barely) in the only publicly-known footage of the toy show that shows Sega's booth. Naka appears to be correct on this point.
- Surviving evidence suggests that this demo wasn't actually playable, much like subsequent autodemos of Sonic the Hedgehog 2 for Game Gear and Sonic Adventure for Dreamcast. An article in Electronic Gaming Monthly #26 (June 1991) described the TTS '90 build as a "self running, one screen demo" (in this case, "one screen" being a reference to the demo's only level, Green Hill), and the surviving screenshots appear to corroborate this.
- However, Naka stated in a 2011 interview with GamesRadar that the TTS '90 build "was something that was playable". EGM #29 (September 1991) also quotes Naka stating that the TTS '90 build was a "playable demo" intended "to show what [the finished game] would be like."
The image on the right shows a controller connected to the console that is running the demo, though it doesn't necessarily confirm that the demo was playable.
Also, during the above GamesRadar interview, Naka claimed that this demo was slated for inclusion in Sonic Mega Collection, but he was unable to find the ROM in Sonic Team's archives.
Sega Logo
The demo begins with an animation of the Sega logo exploding into existence. According to the magazine text, there are 2 explosion patterns.
Title Screen
In this version of the title screen, the letters are differently sized, the ring surrounding the title screen shows more at the bottom, and Sonic's facial expression is different in his final two animation frames. His spines are also shaded differently, making them appear flatter and more "mohawk"-like. There is also no trademark symbol or copyright notice.
In the final game, Sonic's first animation frame is cut off to the bottom left as a byproduct of the technique used to make him appear "behind" the banner; They placed a bunch of invisible sprites there to exceed the sprite limit and cause nothing to render within that area. However, there is no cutoff in this demo, implying that the effect was achieved in a different manner, possibly by having the ring and banner be on separate background layers. It is thought that the change of method was done to free up one of the hardware's two layers and use it to display Green Hill Zone's background here. It also appears that the "Press Start Button" has not yet been implemented.
Green Hill Zone
The demo features Sonic running through what eventually became Green Hill Zone. Unlike in the final game, the background features large mountains and some unusual blue structures, likely buildings based on some early concept art by Naoto Ohshima (seen on the right). These blue shapes appear to scroll faster than the mountains, similarly to the river in the final game's Green Hill Zone. The apparent color of the sky is wildly inconsistent due to the various sources of these screenshots, but it may have been a darker shade of blue compared to GHZ's sky in the final game. Magazine blurbs claimed that this demo featured seven layers of parallax scrolling, including palm trees and boulders in the foreground. These foreground objects would not make it to later public appearances of Green Hill. The top of the palm tree sprite was redrawn in the final game.
The clouds appear to be sprites that scroll independently in the foreground. Because of this, they overlap everything onscreen. In the final game, the clouds are part of the background instead. In the original release, they remain stationary, but a revision would add scrolling back in. The one cloud sprite in this demo had its individual tiles chopped-up and rearranged to create different-looking clouds in the final game.
Despite the screenshots originating from many different magazines, every single one appears to depict the exact same run-through of the level. This is likely evidence for the demo being automated.
[1] What appears to be the starting area of the demo. Sonic's idle pose is different, as is much of the scenery of the stage.
[2]The clouds in the background appear to automatically scroll from right-to-left, as the cloud has moved even though Sonic is still in the same position as the previous screen.
[3]Sonic begins walking to the right.
[1] Sonic comes to a stop again on encountering a hopping blue enemy creature wearing red gloves. Its design (but not its color scheme) was taken, again, from Ohshima's concept art, and was never seen again after this demo.
[4] Sonic continues to the right, running underneath the enemy to avoid its attack.
[5]Another sprite for the enemy.
[1]Although heavily cropped, this shows the enemy after having landed from its jump. The enemy has turned to face Sonic as he continues to the right.
[4]Although also heavily cropped, this shows another Sonic sprite that is very different.
[1] There is a large, flashy sign with text reading "YOU ARE - WELCOME - NEVER OPEN," presumably a joke on "always open," that does not appear in the final game.
[3] Sonic encounters another enemy and, according to the magazine, jumps to avoid it. No unique sprites were assigned for jumping at this point, with Sonic remaining in his walking animation instead.
[4]More one another sprite for the enemy.
[1]The same location as the previous two images.
[3] Sonic passes another sign.
[1] In what is likely the end of the demo, Sonic runs beneath large red Japanese text floating in midair, which says デビュー接近 ("debut approaching").
[5]The large text remains static even though the screen is scrolling.
This shot was cropped from a photograph of SEGA's booth at the June 1990 Tokyo Toy Show, in which the demo can be seen running on-screen in the background.
This is another off-screen shot of the demo from a photograph at the Tokyo Toy Show - however, unlike the previous image the screen contents have come out dark and unclear. To aid visibility, this cropped image has been modified to increase its brightness and contrast. It is unknown which area of the stage this shows, but it's likely the area where the first enemy jumps over Sonic - you can see the foreground tree and the large background mountain to the right of the screen, with what looks like Sonic just starting to be overlapped by the tree's leaves. Just left of these, you can make out a shape which matches the size of the bush in relation to the tree, and something smaller overlapping its left-hand side - from the other available screenshots, this is likely the enemy, having landed on the ground and turned to face Sonic.
[1] Additional image.
[1] Another additional image.
Sprite Changes
The sprites of Sonic shown at the Tokyo Toy Show went through some changes for the final game.
| Prerelease | Final |
|---|---|
 |
 |
His title screen sprite shows off a bit more 'tude in the demo, and sticks closer overall to Ohshima's original concept art. The box art for the American release appears to be based off this early sprite.
- His eyes are positioned differently.
- His second back spine has different shading, giving the appearance of a "mohawk."
- The eyebrow shape and its shadow are different.
| Prerelease | Final |
|---|---|
 |
 |
His in-game sprites differ a bit more:
- There's less shading, most noticeable around and on his spikes.
- His ears are facing forward in the demo. They were changed to face the camera at an angle in the final game.
- Sonic's eyes are slightly more slanted in the demo.
- In the demo, the blue bit of fur that goes around Sonic's eye from the side of his head goes further down, reaching his muzzle.
