B2recomp

by K0NL

B2recomp (short for Bayonetta 2 Recompiled) is an unofficial static recompilation of Bayonetta 2 (Nintendo Switch) for Windows. It translates the Switch version's AArch64 program code to C on your own PC, from your own legally dumped copy of the game, and runs it natively on Windows with a re-implemented system layer (threads, file system, audio, input, and the NVN graphics API on Vulkan).

It is not an emulator (no CPU interpreter, no JIT) and it is not a way to get the game.

This repository contains no game code, no game assets, no Nintendo SDK code, no firmware, no system fonts and no encryption keys, and it does not tell you where to get any of them. It cannot do anything without a copy of the game you dumped yourself from a console and a game you own. Everything derived from the game (the translated code, the compiled game DLL, icons, shaders, textures) is generated on your PC from your dump and must stay there. Please do not share it, and do not open issues asking for it.

Status

Measured on the developer's PC (Windows 11, 16 threads, a Vulkan 1.3 GPU):

What	Result
Title screen, attract sequence, new game	runs
Prologue (cutscenes, chapter card, first fights)	played through: 900 s, no crash, every system call the game makes handled
Chapter 1 with a controller (DualSense, Xbox, Switch Pro and other SDL3 pads)	played by hand past the first part
Standard test run (scripts/bench.py: tutorial and the first fight, scripted)	59.5 fps at 60 and 119 fps at 120 (the display rate), 0 faults
Frame rate 120 (beta)	the test fight at 119 fps on a 238 Hz monitor, each frame shown for two refreshes; combos, hit-stop, Witch Time, slow motions and stick-motion moves (back-forward, double tap) keep their 60 fps timing
HDR (Windows HDR on)	the picture goes out as HDR10, as bright as Windows' SDR content brightness, at no measurable cost (tested on an NVIDIA card)
PlayStation / Xbox button pictures (with the prompt mod)	with Face buttons by printed letter they follow the printed letters, the action prompts in play included (tested with a DualSense)
Later chapters	being played and tested
Other PCs and GPUs	run by players on AMD Radeon cards (RX 560 to RX 9070 XT), on Windows 10 and on handheld PCs; fixes for their reports are in v0.2.1 to v0.2.6 and v0.3.4

Expect bugs. Builds are compared with a scripted test run (python scripts/bench.py, see BUILDING.md).

The game is never downloaded

There is no prebuilt game, no game.dll, no game_native.exe to download, and there never will be: the game is translated and compiled on your PC, from your files. What you can download is this source code, either alone or as the builder package: the same source plus the free tools the build needs, so you install nothing.

What you need

• Your own extracted copy of Bayonetta 2, version 1.2 (update v131072) applied (the ExeFS and RomFS as plain files; see BUILDING.md). The build checks that it is exactly that version and explains a mismatch. Encrypted packages (.nsp, .xci, .nca, ...) are refused: this project decrypts nothing and reads no keys.
• Windows 10/11 x64 and a GPU with a Vulkan 1.3 driver. A Linux version is in testing (the Linux builder on the Releases page, with its own START HERE.txt).
• AMD Radeon RX 400 / 500 cards (Polaris): AMD's Windows driver for these cards lacks Vulkan features that B2recomp's renderer normally uses (dynamic vertex input and pipeline libraries), and it offers no mailbox vsync. B2recomp works around that on Windows: the game runs (confirmed on an RX 560), but its first runs build more shaders while you play, so expect short hitches until they are cached, and vsync waits for the screen (FIFO). This is the driver, not your card: on Linux the Mesa driver (RADV) has all of these features, so the same card runs the full renderer there. If you have Linux on that PC, the Linux version is the better choice for these cards. (Their speed in fights is often set by the processor these PCs have: a 4-core CPU from around 2013 gives a steady 30 fps there.)
• With the builder package: nothing else. From the source alone: Python 3.10+ and the free tools listed in BUILDING.md.

Getting started (step by step)

1. Have your dump ready. One folder that holds exefs\ and romfs\, extracted from your own copy of the game with update 1.2 applied (plain files, not an .nsp or .xci). Put it where it can stay: the game reads romfs\ from there every time it runs. Optional: sysdata\fonts\ with your console's system font (BUILDING.md); without it a font of your PC stands in.

2. Get the builder. Download B2recomp-builder-<version>.zip from this repository's Releases page and unzip it to a folder of its own, with about 1.5 GB free. It holds no game files: only this source, the compiler and the tools the build needs, so you install nothing.

3. Build the game. Start B2recomp.exe. Click Browse... and choose your dump folder (or drag the folder onto the window); it tells you at once whether the folder looks right. Press Build and wait, about 5 minutes on a fast PC. If something is wrong, the window says what (for example the wrong game version); Logs folder has the details.

4. Set it up. When the build is done, the window turns into the launcher. Good first settings:

Setting	What to choose
Window mode	Borderless window or Fullscreen to fill the screen; Windowed with a size you like
Resolution scale	1.5 for a 1080p screen, 2.0 for 1440p, 3.0 for 4K (strong graphics cards only)
Aspect ratio	Keep 16:9 (black bars on an ultrawide screen) or Stretch
HDR	Auto: with Windows HDR on, the game is shown in HDR10, as bright as Windows' SDR content brightness (Settings > System > Display > HDR); with HDR off nothing changes. Off keeps the old look
Frame rate (beta)	60 is the game as made. Up to 120 for a high-refresh screen: timers, combos and slow motions keep their 60 fps timing, and on Windows a 120 Hz or 240 Hz screen shows every frame evenly. Still a beta: some effects and menus may run faster
Preset	Low only for a weak or laptop graphics chip
Vertical sync, Input latency	leave them as they are

Hover over any setting for a short explanation. Press Save (Play also saves).

5. Choose your controls.

• Controller (DualSense, DualShock, Xbox, Switch Pro and most others): connect it before you press Play. "Face buttons" decides whether A is the right button (as on a Switch) or the button printed A (on a PlayStation pad, By printed letter makes Cross A, Circle B, Square X and Triangle Y). Test controller... shows whether your pad is seen; Remap controller... fixes a pad whose buttons are mixed up.

• PlayStation or Xbox button pictures (optional): the game shows Switch buttons. Download Controller Prompts Replacement (DS4/XBOX) by Timo654 (GameBanana 360121, the Switch version), unpack it and put its DS4Prompts and/or XBOXPrompts folder into the mods\ folder beside B2recomp.exe (make the folder if it is not there). With Button prompts on Auto the game then shows the buttons of the controller you play with; or choose PlayStation or Xbox. It is chosen when the game starts. With Face buttons on By printed letter (or a remap that puts A on the bottom button) the pictures follow the printed letters, so Cross is shown where the game asks for A, and the action prompts in play ("Check", ...) show the button where it sits on your pad (Triangle / Y at the top).

• Keyboard and mouse work at the same time as a controller, with a layout like the original Bayonetta on PC:

  Action	Keys
  Move	W A S D
  Camera	mouse (or the arrow keys)
  Punch / Kick	left mouse / right mouse
  Jump	Space
  Shoot	E or middle mouse
  Dodge (and Witch Time)	left Shift
  Lock-on	left Alt
  Umbran Climax	Q
  Pause	Esc
  Menus: confirm / back	Enter / Backspace

  Keyboard and mouse... changes any key: click a slot, then press the key or mouse button you want (Delete clears it). The same window sets the mouse sensitivity and can turn the mouse camera off. In game the cursor is hidden and kept in the window; Alt+Tab lets it go. Input (top of the controller panel) can lock the game to the keyboard and mouse only, or to the controller only.

6. Play. Press Play. The first start takes about 10 seconds longer, and the first time you see a new place the game can hitch briefly while it prepares its graphics; this is saved, so it happens only once. Your saves are in build\play\userdata.

Next time: start B2recomp.exe and press Play. Keep the dump folder where it was.

Updating to a newer version: close B2recomp, then unzip the new B2recomp-builder-<version>.zip to the same place as the old one, so that its B2recomp folder goes over your old one (choose to replace the files when Windows asks). Your saves, settings and mods stay. Start B2recomp.exe: it sees the update and shows the build screen; press Build (a minute or two: only what changed is built again), then Play.

Mods (optional). Put mods made for the Switch version (emulator mod folders) into a folder mods\ beside B2recomp.exe, then click Mods... to switch them on or off. Texture, model and sound mods work at the next start. Code mods (.pchtxt, .ips) need Apply (rebuild): about a minute, with the game closed. Details: BUILDING.md.

If something goes wrong:

• Black window or a Vulkan error at start: update your graphics driver.
• Too dark or too bright with Windows HDR on: move Windows' SDR content brightness slider (Settings > System > Display > HDR; the game follows it while it runs), or set HDR to Off in the launcher.
• Keys or the controller do nothing: click the game window first (input is read only while it is in front).
• The build says the version is wrong: extract again with update 1.2 (v131072) applied.
• "File in use" during a rebuild: close the game and press the button again.
• More: BUILDING.md, Troubleshooting.
• To ask for help: press Report... at the bottom of the launcher (or of the build screen). It makes b2recomp-report.zip in the B2recomp folder with the logs and your PC's details (Windows version, CPU, graphics card and driver), nothing of the game. Attach it to an issue with a few words on what happened.
• Rules for issues: write the issue in English and attach b2recomp-report.zip (Linux: b2recomp-report.tar.gz). An issue that is not in English or has no report attached is closed promptly. (This does not apply to notices from rights holders; see Legal.)

Building from the source

The builder package does all of this for you. To build from a clone instead, with the tools installed yourself:

git clone <URL of the B2recomp repository>
cd B2recomp
python scripts/setup.py --dump <your dump folder>

It is one command with resumable steps; about 5 minutes on a 16-thread PC and 0.8 GB in build/. Then start build\launcher.exe (the same launcher as B2recomp.exe; scripts\play.ps1 starts the game from a console). Details, options, measured times and troubleshooting: BUILDING.md.

targets/, build/ and cache/ (and the generated files in runtime/gen/) hold material made from your copy of the game. They are ignored by git: never commit, upload or share them.

Credits and licence

• B2recomp is made by K0NL: the Bayonetta 2 port of the lifter and runtime, the launcher, the build (setup.py, llvm-mingw), the test run and the tools in scripts/.
• AI helped in reverse engineering the game, with Ghidra and the open-source project REA.
• Reverse-engineering tools, with thanks: Ghidra (NSA, Apache-2.0) with Adubbz's Ghidra-Switch-Loader, and REA by morluto (MIT). None of them is included in this repository.
• The lifter (lifter/) and the runtime (runtime/) started as copies of ssbu-recomp by Denkishi (commit 3a96916), licensed GPL-3.0-or-later; every change is marked [Recomps#1] and listed in runtime/UPSTREAM.md and lifter/README.md.
• Contributions, with thanks: Zexyen, write watch on Linux: the kernel tracks which pages the game wrote, so the textures are no longer checksummed every frame (runtime/linux/win32_compat.c, userfaultfd + PAGEMAP_SCAN; #48).
• Other open-source components and references: see NOTICE.md.
• Copyright (C) 2026 K0NL, the contributors named above for their contributions, and the ssbu-recomp authors for the parts taken from it. This project as a whole is licensed under the GNU General Public License, version 3 or (at your option) any later version; see LICENSE. The need for your own game dump is a technical requirement, not a licence term.

Legal

B2recomp is not affiliated with, endorsed, sponsored or approved by Nintendo, PlatinumGames or SEGA. Bayonetta, Nintendo Switch and related names are trademarks of their respective owners and are used here only to say which software this project is compatible with. No copyrighted game data, Nintendo SDK code, firmware, system data or console keys are included or linked, and this project does not describe how to obtain them. This is a non-commercial project: no donations, paid builds or advertising.

Rights holders with a concern can open an issue on this repository's Issues page, or use GitHub's own takedown process.

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