View source for Sonic the Hedgehog (16-bit) (prototype)/Hidden content

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'''TODO:'''
*Unused level chunks
*Unused debug/edit mode features from earlier builds
*Unused/early GHZ layout data
*Perhaps stuff that would go unused in the final too, for completion's sake

==Level select==
{{HiddenContent
| image1=Sonic1Proto MD LevelSelect.png
| desc=Enabled by default. Simply press {{A}}+{{Start}} on the title screen.
}}

==[[Edit mode]]==
{{HiddenContent
| image1=Sonic1Proto MD DebugMode.png
| desc=Enabled by default. Highlight a Zone in the level select and press and hold {{A}}.
}}

==Unused content==
===Art===
{{UnusedTable|type=Art|offsets=yes|
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite UnusedFont.png}}
| offset=$18000
| desc=An 8x8 font that comes in three different shades of grey.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite Smoke.png|2}}
| offset=$2656E
| desc=Smoke effects{{ref|{{LinkRetro|post=974737|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #974737 by Rika Chou}}}}. Their VRAM spot would be overwritten by the [[Checkpoint|Lamppost]] in the final.{{ref|{{LinkRetro|post=974802|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #974802 by vladikcomper}}}}
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite WaterSplash.png}}
| offset=$26672
| desc=Water splash effects for [[Labyrinth Zone]] that go unused due to a lack of water. In this prototype, the splash has simpler shading and uses Sonic's palette.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite Sparkle.png|2}}
| offset=$267D4
| desc=Sparkle effects.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite UnusedFlame.png|2}}
| offset=$26BF6
| desc=Small flame effects{{ref|{{LinkRetro|post=974737|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #974737 by Rika Chou}}}}.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite EnemyPoints.png|2}}
| offset=$2E6C8
| desc=Combo bonuses awarded from enemies and breakable objects{{ref|{{LinkRetro|post=976355|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #976355 by Nemesis}}}}. All numbers are loaded in VRAM in preparation for combos, but defeating enemies consecutively only awards 100 points in this build.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite BossPieces.png}}<br>{{SpriteImage|Sonic1Proto MD Sprite BossSpring.png}}
| offset=$60864
| desc=An assortment of parts for the [[Egg Mobile]]. While most of the parts here eventually see use for the bosses in the final game, there is a spring attachment that never saw use{{ref|{{LinkRetro|post=974737|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #974737 by Rika Chou}}}}. The second image is an attempt at assembling the spring attachment.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite SpecialStage SkullBlock.png}}
| offset=$6512E
| desc=Skull block for the [[Special Stage (Sonic the Hedgehog 16-bit)|Special Stage]]{{ref|{{LinkRetro|post=974732|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #974732 by Rika Chou}}}}.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite SpecialStage UBlock.png}}
| offset=$651FE
| desc="U"/magnet block for the [[Special Stage (Sonic the Hedgehog 16-bit)|Special Stage]]{{ref|{{LinkRetro|post=974730|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #974730 by Rika Chou}}}}.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1 MD Sprite Emeralds.png|2|crop_x=32|crop_width=16}}
| offset=$65B76
| desc=A [[Chaos Emerald]] for the [[Special Stage (Sonic the Hedgehog 16-bit)|Special Stage]]{{ref|{{LinkRetro|post=976356|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #976356 by Nemesis}}}}.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite UnusedUFOFrame.png}}
| offset=$6C8A0
| desc=An unused animation frame for the UFOs in [[Marble Zone]]. Use [[sega:Action Replay (Mega Drive)|PAR]] code {{hex|011430:0006}} to restore it in the animation script{{ref|https://tcrf.net/Proto:Sonic_the_Hedgehog_(Genesis)#Unused_Sprites}}.
}}
}}

===Objects===
====Placeable in [[edit mode]]====
{{UnusedTable|type=Art|ids=yes|
{{UnusedRow
| content={{spriteImage|Sonic1 MD Sprite Monitors.png|crop_width=30}}
| id=
| desc=Static [[monitor]] that does nothing when broken.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite Splats.png}}
| id=4F
| desc=The infamous [[Splats]] enemy, placeable in [[Marble Zone]]. This [[Badnik]] is fully coded in this build, and when placed it continually bounces forward, only changing direction when it hits a wall. While it uses Sonic's palette line in the object list, it uses the second palette line when placed.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite PurpleRoller.png}}
| id=
| desc=[[Roller (Sonic the Hedgehog 16-bit)|Roller]] enemies for [[Spring Yard Zone]]. They are fully functional, and use the second palette line, making them look purple and yellow.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite SLZSeesaw.png}}
| id=5E
| desc=Seesaws for [[Star Light Zone]]. While fully functional, they don't have the spike ball that helps propel Sonic into the air.
}}
}}

====Others====
{{UnusedTable|type=Art|ids=yes|
{{UnusedRow
| content=
| id=02-03
| desc=Two graphicless objects that date back to the [[:File:GD Sonic 1 Yuji Naka.png|earliest stages of the game's development in February 1990]].{{ref|{{LinkYoutube|video=CRphv7x97uw|title=Sonic initial development site.Sega R&D news footage of Feb 1990.}}}} Object ID {{hex|02}} is a "pulsating" object, and {{hex|03}} is a tall rectangular object. Both objects cannot be placed anywhere in a level as they have set coordinates, and cannot be interacted with by the player.
}}
{{UnusedRow
| content=
| id=04
| desc=An animated object similar to ID {{hex|03}}, which can be placed anywhere on the X axis but has a fixed Y axis.
}}
{{UnusedRow
| content=
| id=05
| desc=An invisible object.
}}
{{UnusedRow
| content=
| id=06
| desc=An object that follows the HUD.
}}
{{UnusedRow
| content=
| id=1B
| desc=A static, collisionless object with two variations, but no corresponding graphics. In the final game, this object was replaced with the water surface object for [[Labyrinth Zone]].
}}
{{UnusedRow
| content=
| id=1D
| desc=An unused switch that acts like any other switch that opens a closed passage. It remains unused in the final game.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite EarlyBallHog.png}}
| id=1E
| desc=[[Ball Hog (Sonic the Hedgehog 16-bit)|Ball Hog]], based on its original front-facing design seen in prerelease material, going unreferenced in the object table. They move from side to side, periodically stopping to drop bombs directly downward.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1Proto MD Sprite BallHogBomb.png}}
| id=20
| desc=The bombs dropped by the Ball Hog.
}}
{{UnusedRow
| content=
| id=2A
| desc=A door object, operated by pressing a switch. It also has a variant that is set up to use other tiles, has no collision, and doesn't react to switches. In the final game, this object was replaced with the one-way doors for [[Scrap Brain Zone]].
}}
{{UnusedRow
| content={{SpriteImage|Jaws-spr.png}}
| id=2C
| desc=[[Jaws (Sonic the Hedgehog 16-bit)|Jaws]] enemies for [[Labyrinth Zone]], which exist in the object table but go unreferenced. They are fully functional.
}}
{{UnusedRow
| content={{SpriteImage|Burrobot-spr.png}}
| id=2D
| desc=[[Burrobot (Sonic the Hedgehog 16-bit)|Burrobot]] enemies for [[Labyrinth Zone]], which exist in the object table but go unreferenced. They use the second palette line and do not start buried underground, but are otherwise functional.
}}
{{UnusedRow
| content={{SpriteImage|Sonic1 MD Sprite GiantRing.gif}}
| id=4B
| desc=The [[Giant Ring]] that would transport Sonic to the Special Stage. Its coding is different in that once Sonic touches it, instead of disappearing instantly, he sparkles for a couple of seconds and then "warps" away. The coding is incomplete beyond this point, so Sonic reappears a couple of seconds later. This "warping" code remains [[Sonic the Hedgehog (16-bit)/Hidden content#Warping effect|unused in the final game]]. The warping effect has an object ID of {{hex|4A}}.
}}
}}

===Audio===
====Music====
{{UnusedTable|type=Audio|ids=yes|
{{UnusedRow
| content=
| id=8B
| desc=Ending theme.
}}
{{UnusedRow
| content=
| id=8D
| desc=[[Final Zone]].
}}
{{UnusedRow
| content=
| id=90
| desc=Continue screen. Goes unused in this build as [[Continue]]s are not implemented yet.
}}
{{UnusedRow
| content=
| id=91
| desc=Staff roll medley.
}}
}}

====Sound effects====
Many of the sound effects listed here are unique to this prototype and would be replaced by other sounds in the final.
{{UnusedTable|type=Audio|ids=yes|
{{UnusedRow
| content=
| id=A1
| desc=Similar to the sound played when exiting a Special Stage. Replaced by the checkpoint sound in the final.
}}
{{UnusedRow
| content=
| id=A5
| desc=Used by the unused Ball Hog's bombs when they explode. Remains unused in the final.
}}
{{UnusedRow
| content=
| id=A8
| desc=This sound effect is used by the unused warping effect in this build. Replaced by the aforementioned Special Stage exit sound in the final.
}}
{{UnusedRow
| content=
| id=A9
| desc=A longer, higher-pitched rolling sound. Replaced by the sound for the speed/Reverse blocks in the Special Stage in the final.
}}
{{UnusedRow
| content=
| id=AA
| desc=The splashing sound for entering water; unused as there is no water yet.
}}
{{UnusedRow
| content=
| id=AD
| desc=A duplicate of the Badnik/monitor explosion sound. Replaced by the sound for breathing in an [[Air bubbles|air bubble]].
}}
{{UnusedRow
| content=
| id=B0
| desc=A low-pitched siren sound that loops endlessly. Replaced by the buzzsaw sound effect.
}}
{{UnusedRow
| content=
| id=B1
| desc=A higher-pitched ''Pac-Man''-esque siren that also loops. Replaced by the sound for Scrap Brain Zone's electrical hazards.
}}
{{UnusedRow
| content=
| id=B2
| desc=Some sort of buzzer sound. Replaced by the sound played when Sonic drowns.
}}
{{UnusedRow
| content=
| id=B3
| desc=A rough sound effect that quickly rises and falls in pitch. Replaced by the sound for Scrap Brain Zone's flamethrowers.
}}
{{UnusedRow
| content=
| id=B8
| desc=Similar to the spike sound. Remains unused in the final.
}}
{{UnusedRow
| content=
| id=BA
| desc=Sounds similar to the sound used by the drop targets in ''[[Sonic the Hedgehog 2 (16-bit)|Sonic 2]]''<nowiki>'</nowiki>s [[Casino Night Zone]]. Replaced by the sound for hitting the diamonds in the Special Stage.
}}
{{UnusedRow
| content=
| id=BB
| desc=The sound used for the Labyrinth Zone doors and Scrap Brain Zone trapfloors; unused as those objects don't exist yet.
}}
{{UnusedRow
| content=
| id=BC
| desc=The sound used for the transport tubes in Scrap Brain Zone; unused as they don't function yet.
}}
{{UnusedRow
| content=
| id=BF
| desc=Two quick, harsh-sounding notes that loop indefinitely. Replaced by the [[Continue]] sound.
}}
{{UnusedRow
| content=
| id=C2
| desc=An alternate version of the Badnik/monitor destroying sound. Replaced by the underwater warning bell.
}}
{{UnusedRow
| content=
| id=C3
| desc=A deeper version of the bomb explosion sound heard in the next sound ID slot. Replaced by the sound for entering a Giant Ring.
}}
{{UnusedRow
| content=
| id=C9
| desc=A harsh, vibrating sound effect. Replaced by the sound for finding a hidden point bonus at the end of an Act.
}}
{{UnusedRow
| content=
| id=CA
| desc=Sounds like footsteps walking away. Replaced by the sound played when warping to the Special Stage.
}}
{{UnusedRow
| content=
| id=D1
| desc=A louder version of the [[Green Hill Zone (Sonic the Hedgehog 16-bit)|Green Hill Zone]] waterfall sounds. Cannot be played in the sound test, and completely removed in the final.
}}
{{UnusedRow
| content=
| id=D2
| desc=A strange rhythmic pounding sound that loops endlessly. Cannot be played in the sound test, and completely removed in the final.
}}
{{UnusedRow
| content=
| id=D3
| desc=A fiery noise that progressively oscillates, looping endlessly. Cannot be played in the sound test, and completely removed in the final.
}}
}}

===[[Green Hill Zone (Sonic the Hedgehog 16-bit)|Green Hill Zone]] alternate palette===
{{HiddenContent
| image1=Sonic1Proto MD GHZ NightPalette.png
| desc={{MDPalette
|0400|0000|0400|0600|0822|0C44|0CCC|0666|0444|0000|0C64|0026|000C|0004|0000|00CC
|0400|0000|0204|0406|0608|082C|0CCC|0666|0444|0000|06C0|0260|00CC|0044|0000|0000
|0000|0000|0AAA|0002|0004|0028|004A|008A|0800|0A42|0A86|0AA8|0000|0020|0060|00A4
|0400|0000|0800|0C42|0C86|0CC8|0CCC|0C48|0604|0200|0006|042C|086C|0000|0000|0000
}}
There is an alternate palette intended for Green Hill Zone that exists in the ROM, but is not normally used. By changing ROM address {{hex|0x1AF6}} to {{hex|1D 9C}} and {{hex|0x1AFE}} to {{hex|1D BC}}, or by using [[sega:Game Genie (Mega Drive)|Game Genie]] codes {{hex|XTPA-B4H0}} and {{hex|1TPA-B4H8}}, this palette can be accessed. This palette is almost identical to the one used for the high score screen in the [[Sonic the Hedgehog (arcade game)|Mega Play version]]{{ref|{{LinkRetro|post=980382|title=Sonic Retro forum thread: Sonic the Hedgehog (Prototype); post #980382 by MrLordSith}}}}.
}}

===[[Spring Yard Zone|Sparkling Zone]] early object layout===
{{HiddenContent
| image1=Sonic1Proto MD SZ EarlyLayout Badniks.png
| image2=Sonic1Proto MD SZ EarlyLayout RedButton.png
| desc=An unreferenced object position list that seems to have been for an earlier layout of Sparkling Zone Act 1 can be found at ROM address {{hex|0x729CA}}. To access it, change ROM address {{hex|0x70040}} to {{hex|29 CA}}.{{ref|https://tcrf.net/Proto:Sonic_the_Hedgehog_(Genesis)#Unused_Object_Positions}}

When loaded in-game, this layout has numerous differences, such as a large abundance of Badniks including [[Moto Bug (Sonic the Hedgehog 16-bit)|Moto Bugs]], and a button that flashes red (which would go unused in the final game). Interestingly, some of the object positions seem to match up with [[Sonic the Hedgehog (16-bit)/Development#Sparkling Zone|prerelease screenshots from earlier builds]].
}}

==References==
<references/>

{{S1MDProtoOmni}}