Friday Night Funkin' V-Slice for Nintendo Switch (unofficial)

A homebrew port of Friday Night Funkin' V-Slice 0.8.7, the official engine by The Funkin' Crew, to the Nintendo Switch. The goal is the PC game, 1:1: same songs, charts, stages, shaders, cutscenes and scoring, running natively on the console.

The .nro contains no game assets. On first launch it downloads the official files straight from The Funkin' Crew's repository (FunkinCrew/funkin.assets, at the exact commit of the game version), checks every file against its SHA-256 and starts the game. They can also be copied from a computer.

This project is not affiliated with The Funkin' Crew Inc. or Nintendo. Friday Night Funkin' is © The Funkin' Crew Inc.; its art, music and charts are proprietary and are never redistributed by this project.

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Contents

• Features
• Installing
• First launch: the game files
• Building
• Testing
• How the port is organized
• Status and roadmap
• Licences and credits

Features

• V-Slice 0.8.7 with every week, Weekend 1, the Erect and Pico mixes, Freeplay, Story Mode, Character Select, the results screen and Polymod mods.
• Asset installer: a small .nro (about 80 MB) that downloads the official files from GitHub, resumes after a lost connection or a closed game, and verifies every file before keeping it.
• Cutscenes from the official video files, decoded on a free CPU core by a minimal LGPL build of FFmpeg (H.264, HEVC and VP9; MP4 and Matroska) and converted on the GPU.
• Audio driver for Switch that replaces SDL2's, which can stall for good when its thread runs late; audio recovers after HOME, sleep and long sessions.
• Memory management for the console's heap: large-block region, banded texture uploads, single-copy image decoding and per-stage cache purges, tested week by week against the console's memory budget.
• Clocks: GPU at 460.8 MHz in handheld and 768 MHz docked (the highest speeds Nintendo allows games), with a CPU boost while loading.
• Switch controls: Nintendo button layout and names in menus, HD Rumble, and an options page for Switch settings.

Installing

Requirements:

• A Switch running custom firmware with the homebrew menu (Atmosphère).
• The homebrew menu opened from a game (hold R while launching any title), so the game gets the full amount of memory. Applet mode (from the Album) does not have enough memory for the game.
• About 1.1 GB free on the SD card, and internet on the console or a computer to copy the files.

Steps:

1. Download Funkin.nro from the latest release.
2. Copy it to /switch/Friday-Night-Funkin/Funkin.nro on the SD card.
3. Launch it from the homebrew menu and follow the first-launch screen.

Saves, mods and logs live next to it, in /switch/Friday-Night-Funkin/ (saves/, mods/). Mods use the same format as on PC.

First launch: the game files

When the official files are missing, the game shows what it needs (size and number of files) and offers to download them:

• Files come only from raw.githubusercontent.com/FunkinCrew/funkin.assets/<commit>/…, for the exact version of the game. Nothing else on the console is touched: the files go to /switch/Friday-Night-Funkin/assets/.
• Each file is written as .part, checked against the SHA-256 listed in the build, and only then renamed. A lost connection is retried automatically; closing the game keeps everything downloaded so far, and the next launch continues from there.
• When everything is in place, the game restarts itself through the homebrew menu and loads normally. Later launches skip the check (a few milliseconds).

Without internet on the console: on a computer, download the archive of the official repository at the commit shown on screen (github.com/FunkinCrew/funkin.assets/archive/<commit>.zip), extract it and copy everything inside its folder to /switch/Friday-Night-Funkin/assets/, so that assets/preload/ exists. The game checks the files on the next launch.

Building

Requirements

• devkitPro with devkitA64, libnx, switch-tools and these portlibs:

  sudo dkp-pacman -S switch-sdl2 switch-sdl2_image switch-sdl2_gfx switch-sdl2_mixer switch-sdl2_net \
    switch-mesa switch-glad switch-libdrm_nouveau switch-openal-soft switch-freetype switch-harfbuzz \
    switch-libpng switch-libjpeg-turbo switch-libwebp switch-libvorbis switch-libvorbisidec switch-libogg \
    switch-opusfile switch-libopus switch-mpg123 switch-libmodplug switch-flac switch-zlib switch-bzip2 \
    switch-curl switch-pkg-config switch-cmake

• Haxe 4.3.7, Git, Python 3, make, curl and a host C compiler (gcc). The first build downloads the FFmpeg 7.1 source from ffmpeg.org.

Setup

git clone --recurse-submodules <this repository>
cd Funkin
haxelib --global install hmm
haxelib --global run hmm setup
hmm install                                       # libraries go to ./.haxelib
python3 tools/nx-tools/sync_haxelibs.py           # puts every git library at the commit pinned in hmm.json
haxelib run lime rebuild switch                   # builds liblime.a for Switch

The Switch forks of lime, OpenFL, flixel and hxcpp are pinned in hmm.json. sync_haxelibs.py is needed because hmm checks out the head of a git library's branch instead of its pinned commit.

Build

# Public build: the asset-less .nro with the installer
haxelib run lime build switch -release -DNX_SD_ASSETS
python3 tools/nx-tools/package_sd_build.py        # -> export/release/switch/bin/Funkin-sd.nro

# Test build: same, plus logs, telemetry, autotests and test shortcuts
haxelib run lime build switch -release -DNX_SD_ASSETS -DNX_DEV_TOOLS
python3 tools/nx-tools/package_sd_build.py

# Development build with the assets inside the .nro (no installer)
haxelib run lime build switch -release -DNX_DEV_TOOLS

Notes:

• The first build compiles FFmpeg (tools/nx-tools/build_ffmpeg_nx.sh) into export/nx-generated/ffmpeg; later builds reuse it.
• package_sd_build.py repacks the .nro with a RomFS that only holds lime's asset manifests, the list of official files (with sizes and SHA-256, generated from the assets submodule at the official commit) and the code licence. It fails if anything else would end up inside.
• The assets submodule must sit at the commit of the official tag; the build checks it.
• tools/nx-tools/deploy_switch.sh [file.nro] copies a build to the console over FTP or MTP (after backing up logs and saves).

Testing

• Citron (Switch emulator): ./tools/nx-tools/run_citron_autotest.sh <SCENARIO> <TIMEOUT> runs a scripted scenario in a test build and checks the game's own trace log. Main scenarios: REGRESSION_SUITE, CUTSCENE_SKIP, WEEKEND1_FULL, MEMORY_BUDGET, AUDIO_DRIVER_STALL, SOAK and, for public builds, PUBLIC_SMOKE.
• Installer on PC: tools/nx-tools/installer-test/run_tests.py <manifest> (verification, repair and state) and run_download_test.py <manifest> (a real download from GitHub).
• Isolation check: python3 tools/nx-tools/check_switch_isolation.py proves that the game files compile on every other platform exactly as the official ones.
• Console: test builds write logs/deep_engine_trace.log and logs/installer.log with timings, memory and audio telemetry.

How the port is organized

Path	What it holds
source/funkin/, assets/	The official game and its assets submodule. Switch changes in game files only exist inside #if switch, so every other platform builds exactly the official code.
source/nx/	The Switch port: audio driver, video player, asset installer, memory, clocks, input, telemetry and automated tests.
source/nx/macro/	Compile-time patches applied to lime and OpenFL on Switch, which fail the build if the library code they target changes.
tools/nx-tools/	Build, packaging, deployment and test tools.
docs/SWITCH_*.md	Tracker of builds and incidents, technical status, upstream changes per version and session guide (in Spanish).

Updating to a new V-Slice version is a merge of the official tag plus a check that the isolation checker still reports zero changes outside Switch; the procedure is in docs/SWITCH_TECHNICAL_STATUS.md.

Status and roadmap

Done:

• V-Slice 0.8.7 merged and validated in Citron (regression suite, Weekend 1, memory budget, audio stalls, soak).
• Asset-less .nro with downloader and verifier.
• Native cutscenes from the official video files.

In progress / planned:

• Console validation of the installer (with and without internet, interrupted downloads).
• ASTC textures generated on the console after the download, to cut memory and loading times.
• Performance: internal resolution, garbage collector pauses and animation CPU cost in the heaviest songs.
• Touch controls in handheld mode, like the mobile version.
• Lime 8.3 / SDL3 on Switch (branch feature/switch-lime83-sdl3), to follow upstream's newer input and library features.

Known limitations:

• Mods written for APIs added in flixel 6.2 / OpenFL 9.5 (V-Slice 0.8.6+) may not run until the lime 8.3 work lands.
• Editors (chart, stage, animation) are not included, as on mobile.

Licences and credits

• The game code is © The Funkin' Crew Inc., under the Apache License 2.0; the Switch port code in this repository uses the same licence. Game assets are proprietary to The Funkin' Crew and are not part of this repository's releases.
• The .nro links FFmpeg (LGPL 2.1+, minimal build script in tools/nx-tools/build_ffmpeg_nx.sh), OpenAL Soft (LGPL 2.0+), SDL2 (zlib), curl (curl licence), Mesa, FreeType, HarfBuzz and the other devkitPro portlibs under their own licences.
• This port started from the first V-Slice 0.8.1 Switch port by FunkinNXTeam (ヴェン, Andres_Github and the team), which brought the game to the console for the first time. Thank you for that first attempt.
• Slushi made lime-nx, the Switch backend of lime this port runs on, and hx_libnx, and also made Switch Funkin', a Psych Engine port. This project is a separate port of the official V-Slice engine.
• devkitPro (devkitA64, libnx and the Switch portlibs), Citron for automated testing, and the HaxeFlixel, OpenFL and lime projects.
• Friday Night Funkin' by The Funkin' Crew: ninjamuffin99, PhantomArcade, evilsk8r and Kawai Sprite. Please support the official game.