Proto:Sonic Spinball (Genesis)

The prototype of Sonic Spinball is not much different from the final.

General Differences

 * No sparkle sound effect played during the Sega screen. The propeller sound is also different.
 * Different / glitchy intro. The video also plays before the title screen instead of after.
 * The ROM size is a bit bigger than the final.
 * The title screen lacks a ™ near the Sega copyright.
 * There is no Options screen.
 * There are some different or missing messages from the scrolling bar on the top of the screen.
 * A debug mode can be activated by simply pausing the game and moving with the D-Pad. This is glitchy, however, as items may be stuck on-screen after entering/exiting debug.
 * Different sound effects and music speeds up at some points (especially in bosses).

General

 * Animals that appear from badniks are different.
 * Boss graphics remain mainly intact on defeat.
 * No eruption timer.
 * The safety lids are referred to as "hatchways".
 * Sonic is off-center in the cutscene when collecting an Emerald.

Toxic Caves

 * Falling into the water at the bottom of the stage means instant death, rather than a two-second wait after splashing.
 * There is a layer of sludge around the bucket.
 * Using the switch that moves the bridge up will play a small Sonic 2 sound byte.

Lava Powerhouse

 * Ferrons are called "Forebots".

The Showdown

 * There is an extra badnik.
 * Trigger on the boss is more helpful.
 * The final boss is invincible, likely because the ending sequence had not been implemented yet. Due to this, the game cannot be beaten.

Bonus Stages

 * Very incomplete. Only the Robotnik tooth-bashing level is available, and even then it has different colors and a garbled screen behind him.