MD Sonic The Hedgehog

The port of the Sonic CD demo version, known as v0.02 or prototype 1204, is a unique adaptation of the earliest known prototype of the game for Sega CD, created for a demonstration at the Yuusei Sega World event in Japan on December 4, 1992, nine months before the final version, making it earlier than the previously discovered prototype 510.
This port brings the demo to the Sega Mega Drive, with improvements that fix certain bugs and introduce new features, such as functional time travel, updated sound effects, and a complete Sega screen with a title menu.
Players have access to Zones 1 and 2 of Palmtree Panic (previously known as Salad Plain), including not only level R11A but also the new level R13D with a boss ported from version 510, as well as a bonus level R31A (without objects) and the ability to select levels using the LRLRLR code. However, the port lacks the Time Attack mode, time travel cutscenes, and the full soundtrack, which has been replaced with music from Sonic 1, as the adaptation of the original audio for the Mega Drive's sound chips was not completed. The Good Future levels, which were also absent in the original demo, are not included either.