RSDKv4-Decompilation

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About

Sonic the Hedgehog (1991) and its sequel Sonic the Hedgehog 2 (1992) are Sega Genesis platform games in which Sonic races through side-scrolling levels collecting rings to stop Doctor Robotnik; Sonic 2 introduced Sonic's sidekick Tails and a multiplayer mode. This is a complete decompilation of Retro Engine v4, covering both the game engine and the 2013 remaster menus for Sonic 1 and Sonic 2. It requires assets from an official release, via Sonic Origins on Steam, Epic Games Store, Switch, iOS, or Android, to run. Beyond reproducing the originals, it adds a built-in script compiler, a mod loader and API, and a custom networking system that recreates Sonic 2's 2-player VS mode online.

How it differs from the original

Adds a custom online multiplayer system, with a self-hosted Python server, recreating Sonic 2's 2-player VS mode; lets the normally-unlockable Egg Gauntlet Zone be selected directly from the Time Attack menu; and includes Sonic Mania-style debug and dev-menu tools not present in the original releases.

Getting started

Requires official Sonic 1/2 game assets from a legitimate release. Clone the repository recursively and build with CMake. To play Sonic 2's online multiplayer, run the included Python server script and configure the host and port in settings.ini; the developers note this networking feature is more a proof of concept, and connections can be unreliable.

Known limitations

compatibility: The multiplayer server is unstable and unreliable for connecting to opponents.

Requires original assets. Requires assets from an official release of Sonic 1 & Sonic 2 (via Sonic Origins on Steam, Epic Games Store, Nintendo Switch, iOS, or Android).

Additional notes

Compatibility: Save files from the Android 'pre-forever' mobile release can be copied in and renamed to work with this decompilation.