Sonic the Hedgehog 2

About

Your own cartridge, which the Sonic Retro disassembly reassembles byte for byte, on mdcore, a Mega Drive core Andrew Nakas wrote under the MIT license.

Sonic the Hedgehog 2 is a side-scrolling platform game and the sequel to the original Sonic the Hedgehog. Players control Sonic as he traverses larger, faster-paced levels across West Side Island, collecting rings, defeating robot enemies, and pursuing Doctor Robotnik. The game introduces Sonic's sidekick Miles "Tails" Prower, a two-tailed fox who can be controlled by a second player. It also adds the spin dash move, a competitive split-screen multiplayer mode, and pseudo-3D special stages in which players collect rings to earn Chaos Emeralds.

Description from IGDB.

How it runs

Project

s2disasmDecompilation. The original binary turned back into source code, function by function.By Sonic Retro

Port

andrewnakas.github.ioBy Andrew Nakas · WebAssembly, on the mdcore emulatorOnline since Oct 8, 2026Source: andrewnakas/sonic2-web

Controls

Arrows move, Z, X or C jump, Enter is Start.

Plays with

Keyboard.

You need

Your ROM: Sonic the Hedgehog 2, REV01 or Rev B, .md, .bin or .gen, 1 MiB. You pick the file in the port, which opens it in your browser.

Original

Sega Technical Institute, 1992, Genesis