SegaSonic Cosmo Fighter

SegaSonic Cosmo Fighter is a ride machine for young kids where you fight Eggman in space.

This was considered a holy grail among Sonic game collectors due to its obscurity and how few units remain in the wild; luckily, a machine was found and the ROM was dumped in 2017. An even more obscure (and presumably even rarer) English version for Sega World Sydney was found in 2021 and dumped on February 19, 2023.

This page currently covers the Japanese version.

To do: Document the English version. The game is now emulatable with MAME 0.252.

Section Names#

There are some strings starting at 0x4F2 that would have displayed where the player is in the game. An old initialization routine at 0x390 can be called to display this text in-game, but it tends to corrupt graphics at times. Note that these appear to reference a working title, "Sonic Jet".

SONIC JET : TEST MODE         
SONIC JET : WARNING           
SONIC JET : TITLE             
SONIC JET : DEMO              
SONIC JET : OPENING           
SONIC JET : GAME              
SONIC JET : ENDING  

Debug Functions#

Some debugging functions are in the game fully intact, using controls that are not present on the released machine:

• The flag at 0xFF800A allows the player to pause the game, mapped as P2 Button 1 in MAME.
• The flag at 0xFF8006 controls the game speed. P1 Start decreases this value, while P2 Start increases it.

Regional Differences#

Japan	Australia

Aside from being translated, the English logo also uses rounder edges. Curiously, the SegaSonic branding is left untouched, despite Sega having already secured the Sonic trademark for Japanese arcade releases by 1996.