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Difference between revisions of "Sonic the Hedgehog 2 (8-bit) AutoDemo"

From Sonic Retro

(Differences)
(Listed my findings on which stages do anything interesting.)
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Green Hills Zone is much longer than what is usually shown and almost resembles a completed stage. Underground Zone utilises several tiles unused in the final game, including what is thought to be a tube (similar to those found in ''[[Sonic the Hedgehog (16-bit)|Sonic 1's]]'' [[Green Hill Zone]]) and some sort of building. Sky High Zone also has platforms.
 
Green Hills Zone is much longer than what is usually shown and almost resembles a completed stage. Underground Zone utilises several tiles unused in the final game, including what is thought to be a tube (similar to those found in ''[[Sonic the Hedgehog (16-bit)|Sonic 1's]]'' [[Green Hill Zone]]) and some sort of building. Sky High Zone also has platforms.
  
Given the very early state of the code, there are many bugs affecting Sonic's movements. Loops do not function correctly when entered at the "wrong" speed, less control is afforded to the player while on springs and Sonic can roll simply by ducking and pressing right or left (i.e. there is no initial momentum requirement). It is impossible to die - Sonic can fall off-screen but is almost always able to jump back on, and exiting the playfield on the right pushes Sonic several pixels to the left in an unclean fashion.
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Given the very early state of the code, there are many bugs affecting Sonic's movements. Loops do not function correctly when entered at the "wrong" speed, less control is afforded to the player while on springs and Sonic can roll simply by ducking and pressing right or left (i.e. there is no initial momentum requirement). It is impossible to take damage, though falling off-screen will usually trigger a reset after a few seconds, and exiting the playfield on the right pushes Sonic several pixels to the left in an unclean fashion.
  
 
Many sound effects are incorrect or nonexistent, and the music track never changes. Hills do not affect Sonic's speed in any way, making some areas with rings impossible to reach, and the ring and time counters in the HUD have no effect on the game when they max out.
 
Many sound effects are incorrect or nonexistent, and the music track never changes. Hills do not affect Sonic's speed in any way, making some areas with rings impossible to reach, and the ring and time counters in the HUD have no effect on the game when they max out.
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==Stages==
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Normally, only three stages are shown by the Autodemo, and only the first act of Green Hill Zone can be played in the hacked version; however, Retro user MarkeyJester developed a tool that allows the rom to be modified to place Sonic in a different level by typing in a hexidecimal code for each zone and act (zone 00 act 01, for example, would be the first zone's second act); using this tool, there are eight playable levels, not counting levels that can be played with more than one designation. The following levels are either at least partially playable or manage to load the HUD;
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Zone 00, Act 00: Green hill zone, the stage displayed prominently in the Autodemo's first moments
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Zone 00, Act 01: Another Green hill zone act, which appears to have a similar layout to the final game's Green hill zone act 2.
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Zone 00, Act 02: An early version of Green hill zone's boss act.
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Zone 00, Act 03: An early Sky high zone stage.
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Zone 01, Act 00: Same as 00 03
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Zone 01, Act 01: Another Sky High level
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Zone 01, Act 02: This Sky high stage occurs in a thunderstorm, similar to act 2 of the final, and is displayed in the Auto demo. Unfortunately, Sonic does not start with a hang glider when controlled manually, causing him to immediately fall to his doom in a deep pool of opaque water, similar to that in Sonic 1's bridge zone.
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Zone 02, Act 03: An Underground zone stage with stacked rails, a tube, and a number of buildings.
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Zone 03, Act 00: Same as 02 03, but Sonic starts in a minecart (which he quickly loses).
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Zone 03, Act 01: Sonic starts in a minecart, goes downhill, and goes off the hill. The game will freeze if Sonic falls far enough.
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Zone 03, Act 02: Sonic starts in a falling minecart and falls for several seconds before the game locks up. Note that Sonic will not respond to button prompts while falling.
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Zone 03, Act 03: The full HUD appears, but the rest of the screen is glitched. It is not clear which zone this eventually turned int
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Zone 04, Acts 01 and 02: The ring and time counters appear, but the rest of the screen is a glitched version of the title screen.
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==External Links==
 
==External Links==

Revision as of 16:13, 21 August 2014

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Sonic2AutoDemo GG title.png
Sonic the Hedgehog 2 AutoDemo
System(s): Sega Game Gear
Publisher: Sega
Developer:
Genre: Action

The Sonic the Hedgehog 2 AutoDemo is a Sega Game Gear EPROM cartridge demonstrating the then-upcoming release of Sonic the Hedgehog 2. It was sent to several magazines worldwide for preview purposes. On July 14, 2014, Orengefox obtained a copy of the AutoDemo, and the ROM was released to the public in August.

As the name may suggest, this Sonic 2 AutoDemo is not playable - instead, the demo plays itself, starting with a simplified introduction sequence and title screen (much like the final game), before continuing with Sonic running through an early version of Green Hills Zone (complete with loop), gliding through a largely empty Sky High Zone, and briefly riding one of Underground Zone's mine carts. Following this, a static "Coming Soon" screen appears, and the demo loops from the beginning.

A single music track plays throughout the demo - one not present in the final game. Much is different from the retail release of Sonic 2, most notably the introduction and title screens and the Green Hills Zone tileset. Tails is also completely missing.

Many early screenshots of the game shown during development are thought to originate from this demo - the primary giveaway being that as gameplay is always the same, the ring and time counts at specific points never change. Furthermore as the HUD resets at the start of each of the three sections, Sonic is seen using a hang glider mere seconds into play - in the final game there are no opportunities to use one this early.

The AutoDemo has an internal date code of 1991-12-05, nine months before the final's date of 1992-09-05.

Differences

  • The SEGA screen is different and plays no "SEGAAA" chant.
  • The title screen only features Sonic, who has no animation (but rises from behind the ribbon)
  • The title screen has no sound.
  • The minecart wheel sits above the rail, rather than inside
  • The lightning flashes in sky high zone are different, and are in the priority plane (i.e. in front of the Sonic sprite)
  • The art of Green Hills zone is completely different, being more similar to the credits sequence of the final version
  • Sky High didn't have trees or flowers in this prototype and seems to be an earlier version than the one featured on the magazines
  • Underground zone has many tiles that didn't make the cut, including gray bricks and curvy stone pathways
  • There only appears to be art for 3 levels. Green Hills zone, Sky High zone and Underground zone.
  • The sound of jumping on a spring is the same as the "rolling down a hill" sound.

Gallery

Hacking

Following release, the ROM was quickly disassembled with control restored to the player. Traversing the stages further reveals a number of hidden and non-functioning objects, such as springs (of which only the vertical types function), spikes and breakable walls, as well as more of the prototype tileset and artwork.

Green Hills Zone is much longer than what is usually shown and almost resembles a completed stage. Underground Zone utilises several tiles unused in the final game, including what is thought to be a tube (similar to those found in Sonic 1's Green Hill Zone) and some sort of building. Sky High Zone also has platforms.

Given the very early state of the code, there are many bugs affecting Sonic's movements. Loops do not function correctly when entered at the "wrong" speed, less control is afforded to the player while on springs and Sonic can roll simply by ducking and pressing right or left (i.e. there is no initial momentum requirement). It is impossible to take damage, though falling off-screen will usually trigger a reset after a few seconds, and exiting the playfield on the right pushes Sonic several pixels to the left in an unclean fashion.

Many sound effects are incorrect or nonexistent, and the music track never changes. Hills do not affect Sonic's speed in any way, making some areas with rings impossible to reach, and the ring and time counters in the HUD have no effect on the game when they max out.

Stages

Normally, only three stages are shown by the Autodemo, and only the first act of Green Hill Zone can be played in the hacked version; however, Retro user MarkeyJester developed a tool that allows the rom to be modified to place Sonic in a different level by typing in a hexidecimal code for each zone and act (zone 00 act 01, for example, would be the first zone's second act); using this tool, there are eight playable levels, not counting levels that can be played with more than one designation. The following levels are either at least partially playable or manage to load the HUD;

Zone 00, Act 00: Green hill zone, the stage displayed prominently in the Autodemo's first moments Zone 00, Act 01: Another Green hill zone act, which appears to have a similar layout to the final game's Green hill zone act 2. Zone 00, Act 02: An early version of Green hill zone's boss act. Zone 00, Act 03: An early Sky high zone stage. Zone 01, Act 00: Same as 00 03 Zone 01, Act 01: Another Sky High level Zone 01, Act 02: This Sky high stage occurs in a thunderstorm, similar to act 2 of the final, and is displayed in the Auto demo. Unfortunately, Sonic does not start with a hang glider when controlled manually, causing him to immediately fall to his doom in a deep pool of opaque water, similar to that in Sonic 1's bridge zone. Zone 02, Act 03: An Underground zone stage with stacked rails, a tube, and a number of buildings. Zone 03, Act 00: Same as 02 03, but Sonic starts in a minecart (which he quickly loses). Zone 03, Act 01: Sonic starts in a minecart, goes downhill, and goes off the hill. The game will freeze if Sonic falls far enough. Zone 03, Act 02: Sonic starts in a falling minecart and falls for several seconds before the game locks up. Note that Sonic will not respond to button prompts while falling. Zone 03, Act 03: The full HUD appears, but the rest of the screen is glitched. It is not clear which zone this eventually turned int Zone 04, Acts 01 and 02: The ring and time counters appear, but the rest of the screen is a glitched version of the title screen.


External Links