Sega Master System / Mark III / Game Gear
The only differences between the Image Works and Virgin Games versions of Speedball are within the ROM header and the data for the initial logo screen & title screen.
In the ROM header, the two ROMs have different product codes (IW: 25009, VG: 25013) and different version numbers (IW: 0, VG: 1).
The logo screen is completely different between the two versions:
On the title screen, the Image Works ROM shows "
© MIRRORSOFT LTD 1990" while the Virgin ROM has "
© VIRGIN GAMES 1992 ".
Researched by RetroSpark