CSE2

About

Cave Story is a game by Daisuke "Pixel" Amaya, whose original Windows executable dates to 2005. CSE2 is a decompilation of Cave Story; this "portable" branch ports the engine away from WinAPI and DirectX so it can run on other platforms, including Linux, macOS, Wii U, 3DS, and RISC OS, in addition to Windows. It builds with CMake and supports several swappable rendering and audio backends (OpenGL, SDL2, and hardware-specific backends for the Wii U and 3DS, among others), and can build either the official Japanese release or the unofficial Aeon Genesis English translation.

How it differs from the original

The decompilation was made unusually accurate because the original executable was compiled with no optimizations, leaving very decompiler-friendly assembly, and because a Linux port later shipped with extensive debugging symbols. The project also offers an optional -DFIX_BUGS build flag that fixes bugs present in the original game rather than preserving them.

Getting started

Build with CMake for the target platform (standard desktop builds for Windows/Linux/macOS; Wii U and 3DS builds require devkitPro toolchains and extra conversion steps to produce runnable .rpx/.3dsx files). The built executable and required data end up in the game_english or game_japanese folder depending on the language chosen at build time.

History

The decompilation was made possible because Cave Story's original Windows executable was compiled without optimizations, and because a 2007 Linux port by Simon Parzer and Peter Mackay — updated in 2011 — accidentally shipped with extensive debugging symbols (original function, variable, and struct names). The 2018 public release of Pixel's Organya music engine further helped document the audio code.

What you need to run it

Media

Licensing & legal

• Because this is a decompilation, most of the code is proprietary and belongs to Daisuke "Pixel" Amaya; only the project's own modifications and custom code are separately licensed, under MIT.

FAQ

What is CSE2?

CSE2 is an open-source decompilation of Cave Story. Source code reconstructed from the original game's compiled binary, so the game can be understood, rebuilt and ported. The original game ran on Windows.

Do I need the original game files to run CSE2?

According to the project's README, no original game files are required.

How is CSE2 licensed?

Daisuke "Pixel" Amaya: proprietary (majority of the code in this project); project: MIT (modifications and custom code). The repository itself is the authoritative source.