Sonic 1 Mixed Beta 1.3.1

Sonic 1 Mixed Beta 1.3.1 is a fan-made ROM hack for the SEGA Genesis that pulls together level layouts, graphics, and mechanics from early beta versions of Sonic the Hedgehog. It's not an official release or a simple prototype; think of it as a curated compilation of unused and altered content stitched into a playable experience. The hack exists thanks to the community around Sonic research, which has documented and restored cut material from the game's development. It's a platformer through and through, but one that intentionally deviates from the final 1991 retail product. Players control Sonic through Zones that loosely follow the original structure, but each stage feels different. Some areas have alternate paths, missing spikes, or test objects that were scrapped before launch. The physics are similar to the original Genesis game, but certain elements like loop-de-loops or enemy placements may behave unexpectedly because they come from unfinished builds. Collecting rings, defeating badniks, and reaching the goal post remains the core loop, but you'll encounter sights and sounds that never made it into the cartridge you grew up with. What makes this hack worth a look is its archaeological value. If you've ever wondered how Sonic 1 looked before the final polish, this gives you a direct window into that era. It's not a polished standalone game - some textures are rough, and the difficulty can be uneven - but for fans of the series or anyone interested in how platformers evolve during development, it's a fascinating time capsule. Compared to other Sonic hacks, it's more of a restoration than a total conversion, which makes it approachable for players who just want to see what might have been.