- Back to: Sonic the Hedgehog (16-bit) (prototype).
The protoype uses the generic Sega logo screen commonly used for most other Mega Drive games, with no Sega Scream present.
The "SONIC TEAM PRESENTS" screen is not present yet. The game goes straight to the title screen from the Sega logo.
The "PRESS START BUTTON" prompt is enabled by default in this prototype. It would be disabled in the final due to an oversight with the "SONIC TEAM PRESENTS" screen. There is also no ™ symbol regardless of the console's region.
The level select displays the early names for each of the Zones, with "X"s next to all of Star Light Zone's Acts and Clock Work Zone Act 3 - the latter cannot be selected, but all of Star Light's Acts are still playable. Final Zone is also missing.
Attempting to play sound 92 crashes the prototype. In the final, this ID is used for the air countdown music.
Title cards have a period present after the word "ACT".
Rolling demos appear to be using older recordings from an earlier build, as Sonic dies almost immediately from enemies. The Special Stage demo also plays inbetween every Zone rather than being at the end of the demo order.
Sonic's jump height is lower. On flat ground, the apex of his jump is 6 pixels lower than in the final.
Walking/jumping onto objects such as platforms and bridges causes Sonic to lose some of his speed.
Extra lives are awarded at 50 and 100 Rings, rather than 100 and 200 Rings in the final. These bonuses can be awarded again by collecting another 50 & 100 Rings after losing them.
There is no combo bonus for destroying multiple Badniks in a row yet.
Invincibility cannot protect Sonic from spikes.
There are no lampposts in the game, so whenever Sonic dies, the player always restarts from the beginning of the Act.
The vertical camera is extremely buggy. In most cases, the camera is too slow to track Sonic when he falls or travels vertically at fast speeds, such as the ramp at the start of Sparkling Zone Act 1.
If Sonic falls down a pit, he wraps around to the top of the map, even in levels which normally don't utilise vertical wrapping.
In levels with lethal pits, the pit oddity described above will cause Sonic to die if he goes past the top level boundary (since Sonic wraps to the bottom of the level, the game thinks he's fallen into a pit).
There are no hidden bonus points at the end of an Act. The Giant Ring doesn't appear either, regardless of how many Rings the player has.
Sonic does not automatically run to the right when finishing an Act. Instead, the player can run around during the score tally. Jumping makes Sonic punch the air in celebration.
There is no Time Over. When the timer reaches 9:59, it resets back to 9:00.
When transitioning between two Zones, the game starts decompressing the next Zone's art during the fade-out rather than after the fade-out.
As seen in several prerelease screenshots, the Ring counter in the HUD displays as "RING", with the number positioned slightly to the left. Additionally, the HUD doesn't flash red when Sonic has no Rings or time is nearly up.