SegaSonic the Hedgehog

SegaSonic the Hedgehog
Developer: Sega AM3[1] Publisher: Sega Platform: Arcade (Sega System 32) Released in JP: October 1993[1] Released in UK: September 7, 1996 (untranslated)[2] This game has unused graphics. This game has unused text. This game has anti-piracy features. This game has a prototype article This game has a prerelease article

SegaSonic the Hedgehog was Sonic the Hedgehog, Mighty the Armadillo, and Ray the Flying Squirrel's only game together until the release of Sonic Mania Plus in 2018.

To do: There are loads more sprites that could be included here, including Robotnik's many, many other sprites (Source). Check for other things, like unused sounds or debug menus to uncover. This guy on Twitter has found a plethora of unused content (there may be more tweets): [1], [2], [3], [4]. He has since documented all his findings on his website. Put all of that content on this page (with proper credit of course). Snippets of design document from one of the game's composers.

Sub-Pages

Prototype Info

Prerelease Info

Unused Graphics

Title Graphics

Unused	Used

Early versions of the characters on the title screen, without the shine on the eyes and the nose missing/unfinished. Sonic's quills are also shaped a little different in this early version. While Sonic was seen in the prototype, Ray and Mighty were nowhere to be seen outside of the graphics data.

Player Character Graphics

Some sprites of the characters flexing their muscles, which possibly would have been used when continuing the game. The code to have these animations display in-game still exists, but doesn't appear to be used anywhere.

Unused	Used

Sonic had his face mercifully redrawn to look less like roadkill, while Ray got his patagia enlarged.

Unused	Used

Sonic got his arms reanimated, Ray had his proportions slightly corrected, and Mighty's mouth was slightly redrawn, and his eyes are now closed.

Dr. Eggman Sprites

It seems that Eggman was supposed to use some gadgets and thingamajigs himself to prevent players from reaching him. Probably meant to show up in other stages in Eggman Island more than waiting for the main character(s) to meet him at the computer room in the final level.

Unused Localization Version

Several graphics and tilemaps suggest that SegaSonic the Hedgehog was going to use elements from the franchise's American equivalent for non-Japanese exports. For whatever reason, plans for these seem to have fallen through; although SegaSonic was brought over to SegaWorld London^[3], it was transparently an import.^[2] Investigation by arcade digital archaeologist Suddenデス found that several tilemaps (as in, the code that displays the graphics on-screen) survived for these graphics, suggesting that this localization made it very far in development until it never found an use. The only sprites that appear to be missing are for him riding around behind the title screen, and the intro where he traps the main character(s) while riding on an Eggman-face tank. No English voice samples are present in the game's sound data.

Dr. Robotnik

A largely complete set of sprites of Robotnik, as he appeared on ABC's Sonic the Hedgehog cartoon (generally nicknamed SatAM) and early issues of Archie's Sonic comics.

Even the little details were accounted for to complete the Robotnik experience.

To use this Robotnik design instead of the original, use this MAME cheat:

 <cheat desc="Robotnik Patch">
   <comment>Requires reload to clear</comment>
   <script state="on">
     <action>mainpcb:maincpu.mw@9619e=0b70</action>
     <action>mainpcb:maincpu.mw@96253=0b70</action>
     <action>mainpcb:maincpu.mw@96367=0b70</action>
     <action>mainpcb:maincpu.mw@964a4=0b70</action>
     <action>mainpcb:maincpu.mw@96197=b088</action>
     <action>mainpcb:maincpu.mw@9624c=b088</action>
     <action>mainpcb:maincpu.mw@9635e=b088</action>
     <action>mainpcb:maincpu.mw@963d0=b088</action>
     <action>mainpcb:maincpu.mw@9649a=b088</action>
     <action>mainpcb:maincpu.mw@963dd=b0c0</action>
     <action>mainpcb:maincpu.md@95c18=17235e</action>
     <action>mainpcb:maincpu.mb@961b1=b3</action>
     <action>mainpcb:maincpu.mb@96266=b3</action>
     <action>mainpcb:maincpu.mb@9637a=b3</action>
     <action>mainpcb:maincpu.mw@12b46=8b90</action>
     <action>mainpcb:maincpu.mw@12c35=b128</action>
     <action>mainpcb:maincpu.mw@12c37=b130</action>
     <action>mainpcb:maincpu.mw@12c39=b138</action>
     <action>mainpcb:maincpu.mw@12c3b=b198</action>
     <action>mainpcb:maincpu.mw@12c3d=b1a0</action>
     <action>mainpcb:maincpu.mw@12c3f=b1a8</action>
     <action>mainpcb:maincpu.mw@12c41=b1b0</action>
     <action>mainpcb:maincpu.mw@12c43=b1b8</action>
     <action>mainpcb:maincpu.mw@12c45=b1c0</action>
     <action>mainpcb:maincpu.mw@12c47=b1c8</action>
     <action>mainpcb:maincpu.mw@12c49=b1d0</action>
     <action>mainpcb:maincpu.mw@12c4b=b1d8</action>
     <action>mainpcb:maincpu.mw@12c4d=b1e0</action>
     <action>mainpcb:maincpu.mw@12c4f=b1e8</action>
     <action>mainpcb:maincpu.mw@12c51=b1f0</action>
     <action>mainpcb:maincpu.mw@14057=b000</action>
     <action>mainpcb:maincpu.mw@1405e=9210</action>
     <action>mainpcb:maincpu.mw@1426d=b000</action>
     <action>mainpcb:maincpu.mw@1426f=b008</action>
     <action>mainpcb:maincpu.mw@14271=b010</action>
     <action>mainpcb:maincpu.mw@14273=b018</action>
     <action>mainpcb:maincpu.mw@14275=b020</action>
     <action>mainpcb:maincpu.mw@14277=b028</action>
     <action>mainpcb:maincpu.mw@14279=b030</action>
     <action>mainpcb:maincpu.mw@1427b=b038</action>
     <action>mainpcb:maincpu.mw@1427d=b040</action>
     <action>mainpcb:maincpu.mw@1427f=b000</action>
     <action>mainpcb:maincpu.mw@14281=b048</action>
     <action>mainpcb:maincpu.mw@14283=b050</action>
     <action>mainpcb:maincpu.mw@14285=b058</action>
     <action>mainpcb:maincpu.mw@14287=b060</action>
     <action>mainpcb:maincpu.mw@14289=b068</action>
     <action>mainpcb:maincpu.mw@1428b=b070</action>
     <action>mainpcb:maincpu.mw@1428d=b078</action>
     <action>mainpcb:maincpu.mw@1428f=b080</action>
     <action>mainpcb:maincpu.mw@235f=aff0</action>
     <action>mainpcb:maincpu.mw@2366=8b50</action>
     <action>mainpcb:maincpu.mw@1d302=9858</action>
     <action>mainpcb:maincpu.md@1be67=00172aa5</action>
     <action>mainpcb:maincpu.mw@1d738=12a0</action>
     <action>mainpcb:maincpu.mw@1d731=af98</action>
     <action>mainpcb:maincpu.mw@1d959=af98</action>
     <action>mainpcb:maincpu.mw@1d95d=afa0</action>
     <action>mainpcb:maincpu.mw@1d961=afa8</action>
     <action>mainpcb:maincpu.mw@1d965=afb0</action>
     <action>mainpcb:maincpu.mw@1d969=afb0</action>
     <action>mainpcb:maincpu.mw@1da6e=0100</action>
     <action>mainpcb:maincpu.mw@1da75=af90</action>
     <action>mainpcb:maincpu.mw@1da7c=1290</action>
     <action>mainpcb:maincpu.mw@96cb1=9fd0</action>
     <action>mainpcb:maincpu.mw@96c21=b0f0</action>
     <action>mainpcb:maincpu.mw@96c23=0b80</action>
     <action>mainpcb:maincpu.mw@96c2d=b0f8</action>
     <action>mainpcb:maincpu.mw@96c2f=0b80</action>
     <action>mainpcb:maincpu.mw@96c39=b100</action>
     <action>mainpcb:maincpu.mw@96c3b=0b80</action>
     <action>mainpcb:maincpu.mw@96c45=b108</action>
     <action>mainpcb:maincpu.mw@96c47=0b80</action>
     <action>mainpcb:maincpu.mw@96c51=b110</action>
     <action>mainpcb:maincpu.mw@96c53=0b80</action>
     <action>mainpcb:maincpu.mw@96c5d=b118</action>
     <action>mainpcb:maincpu.mw@96c5f=0b80</action>
     <action>mainpcb:maincpu.mw@96c69=b120</action>
     <action>mainpcb:maincpu.mw@96c6b=0b80</action>
   </script>
 </cheat>

English Dialogue

A complete set of English dialogue bubbles. Interestingly, one of the bubbles has an "Eggman" variant.

To use these dialogue bubbles, use this MAME cheat. For it to work properly you have change the X in "9fX0" at line 27 of the cheat with 4 for the "Robotnik" variant of the dialogue, or with 3 for the "Eggman" variant of the dialogue.

 <cheat desc="English Patch">
   <comment>Requires reload to clear</comment>
   <script state="on">
     <action>mainpcb:maincpu.mw@95772=9f90</action>
     <action>mainpcb:maincpu.mw@95774=0a20</action>
     <action>mainpcb:maincpu.mw@95776=0130</action>
     <action>mainpcb:maincpu.mw@95778=0018</action>
     <action>mainpcb:maincpu.mw@9577a=9f90</action>
     <action>mainpcb:maincpu.mw@9577c=0a20</action>
     <action>mainpcb:maincpu.mw@9577e=0130</action>
     <action>mainpcb:maincpu.mw@95780=0018</action>
     <action>mainpcb:maincpu.mw@95782=9ff8</action>
     <action>mainpcb:maincpu.mw@95784=0a70</action>
     <action>mainpcb:maincpu.mw@95786=0078</action>
     <action>mainpcb:maincpu.mw@95792=9f28</action>
     <action>mainpcb:maincpu.mw@95794=8800</action>
     <action>mainpcb:maincpu.mw@95796=0130</action>
     <action>mainpcb:maincpu.mw@95798=0020</action>
     <action>mainpcb:maincpu.mw@957ea=9f28</action>
     <action>mainpcb:maincpu.mw@957ec=8800</action>
     <action>mainpcb:maincpu.mw@957ef=0130</action>
     <action>mainpcb:maincpu.mw@957f1=0020</action>
     <action>mainpcb:maincpu.mw@957f2=9f28</action>
     <action>mainpcb:maincpu.mw@957f4=8800</action>
     <action>mainpcb:maincpu.mw@957f6=0130</action>
     <action>mainpcb:maincpu.mw@957f8=0020</action>
     <action>mainpcb:maincpu.mw@9579a=9fX0</action>
     <action>mainpcb:maincpu.mw@9579c=8800</action>
     <action>mainpcb:maincpu.mw@957a0=0038</action>
     <action>mainpcb:maincpu.mw@957a2=9f48</action>
     <action>mainpcb:maincpu.mw@957a4=8800</action>
     <action>mainpcb:maincpu.mw@957a6=0130</action>
     <action>mainpcb:maincpu.mw@957a8=0038</action>
     <action>mainpcb:maincpu.mw@85df5=0050</action>
     <action>mainpcb:maincpu.mw@95762=9f58</action>
     <action>mainpcb:maincpu.mw@95764=8800</action>
     <action>mainpcb:maincpu.mw@95766=0130</action>
     <action>mainpcb:maincpu.mw@95768=0020</action>
     <action>mainpcb:maincpu.mw@957c2=9f80</action>
     <action>mainpcb:maincpu.mw@957c4=8800</action>
     <action>mainpcb:maincpu.mw@957c6=0130</action>
     <action>mainpcb:maincpu.mw@957c8=0020</action>
     <action>mainpcb:maincpu.mw@957ba=9f70</action>
     <action>mainpcb:maincpu.mw@957bc=8800</action>
     <action>mainpcb:maincpu.mw@957be=0130</action>
     <action>mainpcb:maincpu.mw@957c0=0020</action>
     <action>mainpcb:maincpu.mw@957ca=a1b8</action>
     <action>mainpcb:maincpu.mw@957cc=8800</action>
     <action>mainpcb:maincpu.mw@957ce=0130</action>
     <action>mainpcb:maincpu.mw@957d0=0020</action>
     <action>mainpcb:maincpu.mw@957d2=9f78</action>
     <action>mainpcb:maincpu.mw@957d4=8800</action>
     <action>mainpcb:maincpu.mw@957d6=0130</action>
     <action>mainpcb:maincpu.mw@957d8=0020</action>
     <action>mainpcb:maincpu.mw@957da=9f70</action>
     <action>mainpcb:maincpu.mw@957dc=8800</action>
     <action>mainpcb:maincpu.mw@957de=0130</action>
   </script>
 </cheat>

Copy Protection

As with so many of Sega's arcade games at the time, SegaSonic the Hedgehog utilizes a variant of the "suicide battery" FD1149 chip on the PCB.

These custom chips are powered by a clock battery, making the replication of the chip near-impossible during the 1990s. When the battery dies/the ROMs are on a board without the chip, the game seems to operate as normal until when a run starts: the game scrolls diagonally on Icy Isle until ending with a game over, making it impossible to play.

Unused Text Strings

Attract Mode Order

Ranking Mode
Title Mode
Demo 1 Mode
Demo 2 Mode

This is located at 0x463 in Rev. A and 0x60D in the final. The entries here correspond to the attract mode within the game.

Removed Debug Tools

Game Mode
Fence Set Mode
Stage Change
Stg St Wait
RING BINUS

Starting at 0x19F9 in Rev. A and 0x254D includes a block of strings which contain remnants of debugging tools. "RING BINUS" might've appeared below the player health icons to label the ring counter, but was probably removed due to it being a waste of space.

Final-Exclusive Strings

PLayer Select

This string only appears in the final build, at 0x27E2. This appears before code related to the character select screen, which would've made it placeholder text.

NAME ENTRY
PLAYER SELECT

These strings also only appear in the final build, specifically at 0x11413E. This was placeholder text below the player icons.

Miscellaneous

These might have been used when setting to multiple coins per one credit, but they don't appear no matter what dipswitch settings are used.

A sprite viewer menu of sorts. Still exists in prototype.

References