Nebula

Nebula

Nebula runs Super Mario Galaxy natively on Windows. It translates the game's PowerPC machine code into C++ ahead of time, compiles that code on your PC from your own copy of the game, and runs it on a native runtime with a Direct3D 12 renderer and Windows audio and input. Nebula contains no Nintendo code or assets; you need your own copy of the game.

Download · Controls · Building from source · Architecture

Not affiliated with or endorsed by Nintendo.

Project status

Nebula is a work in progress. The game is playable from the start, but some areas run below 60 FPS on weaker hardware, some lighting and bloom effects differ from the original, and bugs remain. See Known issues.

AI-generated project

Nebula was built with AI coding agents (Anthropic's Claude). The recompiler, runtime, installer, tests and documentation were written by AI agents and directed, reviewed and tested by the project's author. The game's own logic, including Mario's physics, is not AI-written: it is the original game code, translated instruction by instruction by the recompiler.

How it works

1. Recompiler (crates/, Rust). Reads the game disc or extracted files, checks that it is the supported release (RMGE01, revision 0) and emits C++ for every function in the game executable, the HOME Menu module and the audio DSP program.
2. Runtime (runtime/, C++). Loads the compiled game module and provides what the Wii hardware provided: memory, a GX command processor drawn with Direct3D 12, the audio interface and DSP, Wii Remote input from keyboard, mouse and controllers, disc and NAND storage, and video timing.
3. Installer and launcher (installer/, C#). Nebula-Setup.exe downloads a pinned compiler toolchain, compiles the game modules from your copy of the game and installs the prebuilt runtime. Nebula.exe starts the game; NebulaSettings.exe changes settings.

Features

• Keyboard and mouse, Xbox controllers, the Switch Pro Controller and the Switch 2 Pro Controller (USB), remappable. Switch controllers point with the gyro (R recenters) and tilt for the Star Ball and ray surfing. Vibration follows the game's Wii Remote motor.
• Aspect ratios from 4:3 to 32:9 and internal resolution up to 16x.
• Anti-aliasing (SMAA, FXAA), AMD FidelityFX FSR 1 upscaling, anisotropic filtering and optional per-pixel lighting.
• In-game settings menu (F1, View + Menu on Xbox, Minus + Plus on Switch).
• Saves stored in %LOCALAPPDATA%\Nebula\saves.

Requirements

• Super Mario Galaxy, USA (RMGE01), revision 0, as an ISO, RVZ or extracted folder
• Windows 10 (version 1803 or newer) or Windows 11, 64-bit
• A GPU with Direct3D 12 support
• 8 GB of RAM; 16 GB of free disk space during installation, about 5.5 GB afterwards
• An internet connection for the first installation

The least powerful system tested so far, an Intel Core Ultra 9 185H with its integrated graphics and 16 GB of RAM, runs the game at a locked 60 FPS at 1440p (16:10).

Install

1. Download Nebula-Setup.exe from the latest release. The file is not code-signed, so Windows SmartScreen shows "Unknown publisher"; choose More info, then Run anyway.
2. Select your game and choose Install. Setup downloads the toolchain and compiles the game modules; this takes a few minutes on a fast PC and longer on slower ones.
3. Start Nebula from the Start menu.

Setup also updates, repairs, restores the previous version and uninstalls. Updates are signed; Setup checks the signature against the public key built into it before installing.

Building from source

docs/BUILDING.md covers the tools, building the recompiler, runtime and game modules by hand, running the tests and building the installer.

Testing

• Recompiler: more than 500 tests (cargo test --workspace).
• Runtime: 70 test programs (ctest) covering floating-point operations (checked against Berkeley SoftFloat), GX command parsing and texture decoding, input mapping, the audio queue and DSP, and settings files.
• tools/dev/verify_thp_native.cpp compares the native movie decoder with the game's own decoder frame by frame.
• Gameplay is checked by playing back recorded input in a hidden window and by manual playtesting.

There is no automated whole-game comparison against the original hardware or an emulator yet. Floating-point results are close to, but not bit-exact with, the Wii.

Known issues

• Heavy background CPU load can make the audio skip.
• Some areas, for example the Gateway Galaxy, drop below 60 FPS on weaker CPUs.
• Some lighting and bloom effects in the Comet Observatory differ from the original.

Report problems on the issue tracker.

License

Nebula is licensed under the GNU General Public License v3.0 only (LICENSE). Third-party code and its licenses are listed in THIRD-PARTY-NOTICES.md and docs/PROVENANCE.md.

Nebula builds on work from Aurora, Dusklight, WiiCompiled, the Petari decompilation project, Berkeley SoftFloat, the Dolphin project's free DSP ROM, SMAA, AMD FidelityFX and the nod disc library.

"Super Mario Galaxy", "Wii" and "Nintendo" are trademarks of Nintendo.