Denkishi/ssbu-recomp

OpenSmash-Ultimate

Super Smash Bros. Ultimate as a native PC program: recompiled, not emulated. One-click installer, Vulkan renderer, in-game settings, fighters as readable C++ source, online and rollback in progress.

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The project is called OpenSmash-Ultimate. The repository is still named Denkishi/ssbu-recomp.

This repository contains no game code, no game assets, no keys and no firmware. You need your own legally obtained copy of the game (13.0.4 or 13.0.5). Everything derived from it is generated on your PC, from your dump, and never leaves it. The only game-related text in the tree is names: a list of system-library function names chosen for translation, and function names used by the tools.

OpenSmash-Ultimate is a native Windows port made by static recompilation of Super Smash Bros. Ultimate (Nintendo Switch, version 13.0.4 or 13.0.5). The game's AArch64 machine code is translated to C ahead of time and compiled for your PC. There is no CPU interpreter and no JIT while you play. The console's system libraries, graphics API, audio, video, input and file system are re-implemented by this project's own runtime, and the picture is drawn with Vulkan.

It starts like any PC game, runs in a 16:9 window (F11 for borderless fullscreen), takes any controller, loads its shaders at start, and its fighters can be read and changed as C++ source.

• Native code instead of emulation. The CPU work of "pretending to be a Switch" is gone because the game's code is already x64 when you start it. We make no claim of being faster than any specific project on your hardware; we publish what we measured and how (59-60 fps in fights on an NVIDIA GPU and on an Intel integrated GPU).
• API-level graphics. The game's graphics API (NVN) is translated to Vulkan, and the game's shaders are translated when loaded and prepared on background threads. This keeps the renderer small and tunable. General emulators that reproduce a GPU in detail are more faithful to unusual cases; the two approaches serve different goals.
• Source where people edit. Fighter scripts become readable C++ that is checked against the original in differential tests. That is what a real mod platform and a rollback netcode need: the simulation as code and data you can read.
• Install without ceremony. One double-click, no Visual Studio, no firmware dump.

We learned from many open-source projects (see Credits) and respect all of them.

You need your own game dump and keys. That is all: the installer fetches everything else.

1. Download the game's ZIP: ssbu-recomp-main.zip (the same as the green Code button > Download ZIP), and unpack it, or git clone it. Not the files under Releases: those are build tools the installer downloads by itself.
2. Double-click Install SSBU.bat. It sets up a private Python inside the folder (nothing is installed on your system), checks your PC, and finds your keys and games by itself in the folders of yuzu, Ryujinx, suyu, sudachi and eden. Check what it found and press Install: it applies the update and DLC, uses the prebuilt runtime from a GitHub Release, downloaded by itself (so no Visual Studio), and builds the game files on your PC. No firmware is needed: open-source fonts are included. It makes shortcuts, updates itself, and if it stops, double-click it again and it resumes.
3. Double-click Play SSBU.bat (or the desktop shortcut). Your saves go to build\saves.

Full guide, requirements and the same build done by hand: BUILDING.md.

Status key: Done = works and was tested on the development PC; Experimental = works, not widely tested or off by default; In progress; Planned.

Vulkan pipelines are prepared ahead by background threads from the game's shader containers, with a loading barrier: 0 pipeline holds in fight frames in the first-run tests on an NVIDIA and an Intel GPU (one scripted fight, and three more with other fighters and stages in the fast test mode). A whole match runs on an Intel Raptor Lake iGPU at 59-60 fps. Not shown: every window clean on a cold first run (NVIDIA: 6 frames of 34-38 ms at the very start of one of two fights), and a pixel comparison with the OpenGL renderer. The preparation takes about 15 minutes of play on a first run and costs disk (about 2.5 GB of shader files, up to 0.9 GB of pipeline cache). A freeze that was reported once was not reproduced in long runs; its cause is not established.

your dump --> tools/extract --> main executable, SDK, script modules, data
                 |
                 v
        tools/lifter (recomp.py)        AArch64 -> C, one C function per game function
                 |                       checked against Unicorn on 32,043 instruction cases
                 v
        clang --> game DLL  +  one DLL per script module
                 |
                 v
        runtime/                         what the console provided, re-implemented:
          hostrt, os_threads             loader, threads, memory, C++ exceptions through lifted code
          nn*.c                          ~1,100 system-library entry points (files, time, audio, input,
                                         movies, fonts, applets, accounts, network)
          nvn_vk*.c, nvn_gl.c            the console's graphics API (NVN) on Vulkan / OpenGL
          mx_translate.c                 the game's GPU shader machine code -> GLSL -> SPIR-V
          nnpad_sdl.c                    controllers through SDL3
          nnpad_gca.c                    GameCube controller adapter over WinUSB (shown to SDL as virtual gamepads)

• Game code is recompiled, not emulated: a mechanical translation, complete and exact, but not readable source.
• System calls are re-implemented on Windows, the way Wine re-implements Windows calls.
• Graphics are translated at the API level, and the shaders when they are loaded.

A fighter's moves are small scripts. fighter_sdk/tools decompiles them into C++ like this (generated on your PC from your dump; not stored in this repository):

ACMD(mario, game_attack11) {
    frame(agent, 2);
    if (is_excute(agent)) {
        ATTACK(agent, 0, 0, hash40("top"), 2.2f, 361, 30, 0, 20, 1.2f, 0.0f, 6.3f, 6.0f, /* ... */);
    }
    wait(agent, 2);
    if (is_excute(agent)) {
        AttackModule::clear_all(boma);
        WorkModule::on_flag(boma, FIGHTER_STATUS_ATTACK_FLAG_ENABLE_COMBO);
    }
}

On the development PC the tool turns 80,880 of 84,886 animation-command scripts of all fighters (95%) into source that behaves like the original in a differential test; a fighter rebuilds in about a second. Eight fighters (Mario, Luigi, Link, Samus, Fox, Captain Falcon, Donkey Kong, Ness) run their status source in deterministic matches with identical per-frame logs against the lifted version (2,010 fight frames each). More: docs/MODDING.md.

Is this legal? The repository contains no game code, assets, keys or firmware, and does not help anyone obtain them. You build the program on your PC from a copy of the game you own. This is not legal advice; laws differ by country.

Do I need a Switch? To make your own dump of the game and keys you need a console you own that can run dumping tools, or an existing dump you made legally. This project cannot do that step for you.

Does it include the game? No. Not the game, not the keys, not the firmware, and no links to them.

Which GPU do I need? Any GPU with a Vulkan 1.3 driver. An integrated Intel Raptor Lake GPU played a whole match at 59-60 fps in our tests. Windows 10/11 x64. The movies play with Windows' own VP9 Video Extensions and Web Media Extensions (free, Microsoft Store) when they work, otherwise with FFmpeg, which the installer downloads.

Can I play online? Experimental. The game's Local Wireless mode works over a LAN, a room code or a lobby server: docs/ONLINE.md. Rollback netcode is in progress and is not available yet.

Which game versions? 13.0.4 and 13.0.5 (docs/VERSIONS.md).

How do I use my own save file? With the game closed: the game keeps its saves in build\saves\save\ (or <your install location>\saves\save\ if you chose one in the installer), as a save_data folder holding system_data.bin, mii, spirits and stage. Get your save as a folder that contains save_data: from your Switch with JKSV or Checkpoint, from yuzu / Eden / suyu (right-click the game, "Open Save Data Location") or from Ryujinx (right-click the game, "Open User Save Directory"). Rename build\saves\save to save_old as a backup, create a new empty build\saves\save and copy your save_data folder into it (you should have build\saves\save\save_data\system_data.bin), then start the game. Folders named save.work.<number> are temporary session files: leave them or delete them while the game is closed.

"ssbu_game_eh_o1.dll is missing" when I start the game? The game DLL (about 500 MB, built on your PC and not signed) was removed after the installation, usually by an antivirus, or the installation stopped before the end. Open Windows Security > Virus & threat protection > Protection history and restore/allow the file if it is there (adding your install folder to the exclusions stops it happening again), then double-click Install SSBU.bat and press Resume: it links the missing files again in a few minutes, without compiling everything again.

Mods and new fighters? Mods through the function hook table and C++ fighter source work today; new fighters are in progress (docs/NEW_FIGHTER.md).

Was this built with AI? Yes, see below.

This project was built with AI, and that is part of the point.

I am not a reverse engineer or a security engineer, and I did not come up through whatever field normally teaches this. Almost all of the code here was written by AI coding agents (Claude) that I direct: I decide what to try, think up the angle of attack or the workaround, and the AI implements it quickly and comes back with a result I can check. That loop (an idea, an implementation within the hour, a measurement that says whether it held) is what made a project of this size possible for one person.

What I take from it: the bar for entry has dropped a great deal. The creativity is still yours (which problem to solve, which trick might get around it, when a result is not good enough), but the distance between having the idea and seeing whether it works is now very short.

Two rules kept it honest: every claim has to come from a test or a measurement (this README says what was measured and what was not), and nothing derived from the game goes into the repository. It is a study project; expect rough edges, and mistakes that a specialist would not have made.

Testers with other GPUs and controllers, and people who know the game's internals or the modding scene's tooling, are very welcome. Read CONTRIBUTING.md first: three rules (nothing derived from the game in the repository, clean sources only, every claim measured) apply to every contribution. Questions and bug reports: the Discord or GitHub issues (attach the log from the settings menu and your config\graphics.ini).

• Denkishi, maintainer.
• xtlg511: support for game version 13.0.5, the libopus build step, a run.py fix.
• jfb112697: a setup.py check fix.
• SNO2207 / WindowSmash: parts of the online network code and the lobby design are adapted with the author's permission (see docs/ONLINE.md); the installer's approach was inspired by its tools (nothing copied).
• yuzu and suyu: the open-source system fonts shipped in runtime/fonts_open (README).
• Slippi and Hero88go/melee-unlocked: the public design of rollback netplay that guides our netcode.
• sbergeron42/ssbu-decomp: the matching-decompilation effort (our work on it is paused).
• yuzu and its successors, SDL, glslang, libopus, Unicorn, Capstone, the N64 static-recompilation projects and BelmanteGu/SuperMarioWonderRecomp, from which technique was learned.
• The Smash modding community (param labels, skyline-smash, ARCropolis) for names of script functions and constants.

OpenSmash-Ultimate is not affiliated with, endorsed or sponsored by Nintendo, Bandai Namco or Sora Ltd. Super Smash Bros. and Nintendo Switch are trademarks of their owners and are named only to say what the software works with. The repository contains no copyrighted game data, no console keys and no firmware, and does not help anyone obtain them. You must own the game and dump it yourself. No Nintendo logos or artwork are used.

Licensed under the GNU General Public License, version 3 or later (see LICENSE).