<img src="tools/cia/banner.png" alt="Gen1Recomp 3DS banner" width="512"> <h1 align="center">Gen1Recomp · Lua Native 3DS Port</h1> Pokémon Red, Blue, Yellow, Gold, Silver and Crystal, recompiled in Lua, running natively on the Nintendo 3DS / 2DS. No emulator. Your own cartridge dump, imported once on the PC. Installs as a 3dsx or as a real HOME-menu title. <a href="https://github.com/cohako/gen1recomp-lua-native-3ds-port/releases/latest"><img alt="Latest release" src="https://img.shields.io/github/v/release/cohako/gen1recomp-lua-native-3ds-port?display_name=tag&label=release&color=e4405f"></a> <a href="https://github.com/cohako/gen1recomp-lua-native-3ds-port/actions/workflows/tests.yml"><img alt="Tests" src="https://github.com/cohako/gen1recomp-lua-native-3ds-port/actions/workflows/tests.yml/badge.svg"></a> <img alt="Platform" src="https://img.shields.io/badge/platform-New%203DS%20%7C%20New%202DS%20XL-9cf"> <img alt="Engine" src="https://img.shields.io/badge/engine-L%C3%96VE%20Potion%20fork-ff69b4"> <a href="LICENSE"><img alt="License" src="https://img.shields.io/badge/license-MIT-blue"></a>

This is the 3DS port layer for gen1recomp, the LÖVE/Lua recreation of the Game Boy Pokémon games, built on a fork of LÖVE Potion. Tested on a New 2DS XL with Luma3DS, both as a 3dsx (Homebrew Launcher) and as a CIA (HOME menu). Old 3DS/2DS is untested.


🎮 Plays	Gen 1 end to end through the upstream game: full speed battles, saves, sound effects and cries. Gen 2 loads, but the overworld crashes on the first big map (see Roadmap)
📦 Installs	`gen1recomp-<v>-3ds.zip` for the Homebrew Launcher, or `gen1recomp-<v>-3ds.cia` for a HOME-menu icon
🖼️ Renders	PNG decoded straight into the PICA200's tiled layout, no `.t3x` pre-conversion needed
🧰 Ships	Debug symbols and `sha256sums.txt` with every release
🚫 Contains	Nothing from Nintendo: no ROMs, no firmware, no keys. Your cartridge, your dump.

⚡ Quick start

You need: a 3DS/2DS with Luma3DS, the Homebrew Launcher (or FBI for the CIA), and one thing dumped from your own console:

sdmc:/3ds/dspfirm.cdc — the DSP firmware, required by every homebrew that plays sound. Dump it once per SD card: Rosalina menu (L + Down + Select) → Miscellaneous options → Dump DSP firmware. It lands in the right place by itself. Without it the app exits before drawing anything.

<details open> <summary>Option A — Homebrew Launcher (3dsx)</summary>

Download gen1recomp-<version>-3ds.zip from the latest Release.
Extract it onto the root of the SD card, merging the 3ds folder. You get sdmc:/3ds/gen1recomp.3dsx and sdmc:/3ds/game/.
Build your ROM cache on the PC (next section) and copy the 3ds folder it produces onto the card too.
Open the Homebrew Launcher and start Gen1Recomp.

No card reader? Netload ftpd.3dsx once, then scripts/3ds/ftp_upload_game.py <3DS-IP> uploads the game tree over wifi.

</details> <details> <summary>Option B — HOME menu title (CIA, via FBI)</summary>

Same engine, as its own title: an icon on the HOME menu, no Homebrew Launcher, and about four times the heap the 3dsx gets under the launcher (91 MB measured vs ~24 MB).

Copy gen1recomp-<version>-3ds.cia anywhere on the SD card (or send it with FBI's Remote Install using scripts/3ds/fbi_send_url.py <3DS-IP> <url>).
FBI → SD → the .cia → Install and delete CIA.
Copy your imported ROM folder onto the card (next section). The game tree itself is inside the CIA, so sdmc:/3ds/game/ is not needed; when it exists (the 3dsx install), it wins, so both can live side by side and share 3ds/save/pokemon-love2d.

The CIA holds the assembled game tree (upstream gen1recomp plus this port's changes) and LÖVE Potion, signed with makerom's public test keys, which is why a CFW is required. No Nintendo firmware, keys or assets inside.

</details>

💾 Importing your ROM (on the PC)

The console does not import ROMs (see Limitations); the PC does it in seconds. The release zip ships import-tools/ for exactly this — put that folder next to the gen1recomp desktop app (or install LÖVE), then double-click the file for your system:

System	File
Windows	`import-tools/Export-3DS.bat`
macOS	`import-tools/Export-3DS.command`
Linux	`import-tools/Export-3DS.sh`

No arguments, no questions. It imports every .gb/.gbc you dropped in import-tools/roms through the game's own headless mode, picks up any cache you already imported in the desktop app, writes everything to import-tools/sd-card/3ds/save/pokemon-love2d/<version>/, and prints that path. Copy that 3ds folder onto the card root, merging.

Each version folder holds:

<version>/
  assets/generated/     PNG textures — the engine decodes PNG natively
  data/generated/
  rom-cache.complete    the marker the launcher checks; identical on every platform

The launcher shows a version as ready — readiness is that marker; there is no flag or config on the console. Versions: red, blue, yellow, gold, silver, crystal; the ROM is identified by SHA-1, both Crystal revisions are accepted.

Validated on Linux against the upstream v0.2.64 AppImage: the cache it produced was accepted by the console. Windows and macOS were exercised against a stand-in app only, not on real machines. By hand it is POKEPORT_IMPORT_ONLY=1 POKEPORT_IMPORT_ROM=<rom> love . in a game tree, then copy ~/.local/share/love/pokemon-love2d/<version> (Linux; %APPDATA%\LOVE\... on Windows, ~/Library/Application Support/LOVE/... on macOS).

<details> <summary>🎵 Music (optional)</summary>

The console cannot synthesize the chip music in real time, so map and battle music is silent unless pre-rendered WAVs exist in the cache. Render them on the PC (needs LuaJIT; the script's header shows the Docker one-liner):

luajit scripts/3ds/prerender_music.lua <path/to/version-cache>

Output goes to <version>/assets/generated/audio/music/*.wav; copy it with the rest of the cache, or scripts/3ds/ftp_upload_music.py <IP> --source <cache>. Yellow's full set is ~76 MB.

</details>

🗂️ What is in this repository

This repository does not contain the game. It contains everything needed to build the port from the upstream game:

Path	What
`engine/`	The LÖVE Potion fork (C++), full source. Rendering, audio, input and shutdown fixes for the 3DS, native PNG decode/encode, CIA start-up, the Gen1Recomp SMDH icon.
`overlay/`	New files added to the game: the 3DS platform layer (`src/core/Console.lua`), the console test suites, `scripts/3ds/` (FTP upload, SD mirror, music pre-render).
`import-tools/`	The double-click scripts that build the SD card folder on the PC; shipped inside the release zip.
`patches/`	One diff per upstream game file the port edits (20 files).
`UPSTREAM`	The upstream gen1recomp commit the patches apply to.
`tools/`	`assemble.sh` (upstream + overlay + patches → `work/game/`), `package.sh` (release zip), `cia/` (RSF, banner, icon, `make_cia.sh`).
`docs/`	`instrumentation.md` + two patches: the console probes used during bring-up, removed from the build, re-applicable in one command.

The scripts/3ds/ tools live in overlay/scripts/3ds/ here and inside the assembled game tree (work/game/scripts/3ds/); run them from the latter. import-tools/ is separate: it runs on the PC next to the desktop app, not from the game tree.

🔧 Building

Everything runs in Docker; no toolchain install needed.

# 1. game tree (clones upstream at the pinned commit, applies overlay + patches)
tools/assemble.sh                       # -> work/game

# 2. engine
docker run --rm -v "$PWD/engine":/src -w /src devkitpro/devkitarm:latest \
  sh -c 'cmake -G Ninja -S . -B build -Wno-dev -DCMAKE_TOOLCHAIN_FILE=/opt/devkitpro/cmake/3DS.cmake && ninja -C build'
  # -> engine/build/lovepotion.3dsx + lovepotion.elf

# 3. zip laid out like the SD root
tools/package.sh engine/build/lovepotion.3dsx 0.0.0-local

# 4. CIA (Linux x86_64 only: downloads pinned makerom + bannertool on first run)
tools/cia/make_cia.sh engine/build/lovepotion.elf dist/gen1recomp-0.0.1-3ds.cia v0.0.1

UPSTREAM_DIR=/path/to/gen1recomp tools/assemble.sh reuses a local clone. Console test suites (overlay/tests/engine/*.lua) run with luajit from work/game, same as CI.

CI. tests.yml runs on every push/PR to master (assemble + console test suites). engine.yml (3dsx + ELF + CIA artifacts) runs on PRs that touch engine/ or tools/cia/, and by hand from the Actions tab; it checks that the engine builds and the CIA packs, not that they run. release.yml is manual only. release.yml picks the version (blank input = next patch after the newest tag), builds master, creates the tag and the GitHub Release, and attaches gen1recomp-<v>-3ds.zip, gen1recomp-<v>-3ds.cia, gen1recomp-<v>-3ds-symbols.elf and sha256sums.txt, with the issues closed and contributors since the previous release in the notes — the same shape as upstream's releases. It needs write access and refuses a version whose tag already exists.

<details> <summary>Notes on the engine</summary>

The game is loaded from sdmc:/3ds/game/ when that folder exists. The 3DSX RomFS belongs to LÖVE Potion (shaders and the no-game screen); the CIA's RomFS also carries the game tree, and boot.lua falls back to romfs:/game when the SD has none. A CIA chdirs to sdmc:/3ds at start so both install methods share one layout.
PNG loads natively: decoded straight into the PICA200's 8×8 tile layout; anything above 1024 px is box-filtered down to fit. A sibling .t3x (tex3ds -f rgba8888 -z auto) is still preferred when present.
Fonts use the console's system font; .ttf files are not parsed.
The SMDH title, author, description and icon are set in engine/CMakeLists.txt (platform/ctr/icon-gen1recomp.png, 48×48). The CIA's title version comes from the release tag.

</details> <details> <summary>Updating the upstream game</summary>

Edit the game line in UPSTREAM, run tools/assemble.sh. A patch that no longer applies is named in the output; regenerate it from a checkout with the change re-applied (git diff <upstream> -- <file> > patches/NN-<file>.patch). Run the tests, then verify on hardware.

</details>

🚧 Current limitations

No ROM import on the console. Measured on a New 2DS XL under the Homebrew Launcher: a Gen 2 import took hours (one SD write and PNG encode per file) and then crashed in malloc at 68% — the extractor keeps ~30 MB live in Lua 5.1, more than the heap the 3dsx gets there. The Import button only tells you which folder to copy. The CIA has ~91 MB of heap, but import stays disabled on the console: the PC does it in seconds.
No map/battle music without the pre-render step above. Sound effects, cries and Yellow's Pikachu voice work.
No online features on the console. The mod index, mod downloads and the update check go through a curl subprocess or a native bridge on the other platforms; neither exists on the 3DS, so the Mods tab cannot fetch anything. (LÖVE Potion does ship https; wiring it in is future work.)
Top screen only (400×240). The bottom screen is unused.
Tilt effect disabled (its 741×573 canvas does not fit VRAM). Palette effects run without shaders.
The New 3DS C-stick is not read (the engine never initialises irrst). D-pad, Circle Pad, buttons and touch work.
Performance: the GPU is mostly idle; frame time is interpreted Lua on the main core. Battle/encounter transitions are noticeably slow.
Memory: the CIA gets 91 MB of heap + 32 MB linear (measured). Under the Homebrew Launcher the split is inherited from the host title, roughly 24 MB + 32 MB by libctru's defaults (not measured). VRAM is 6 MB either way.
Azahar/Citra cannot be used to test: LÖVE Potion exits immediately under it (lovebrew/LovePotion#102) while the same build runs on hardware.
Upstream pinned to fdd1d61e (dev, 2026-09-05). Newer upstream releases need the patches refreshed.
Tested on a New 2DS XL only. The CIA asks for the New 3DS memory mode (SystemModeExt: 124MB); an Old 3DS/2DS is untested.

🗺️ Roadmap

Work on the port itself, roughly in order:

Gen 2 overworld on the console. Upstream bakes each map into a canvas through a palette shader; the PICA200 has no fragment shader and a map-sized canvas does not fit the 6 MB of VRAM, so the overworld crashes on the first big map. The fix in progress bakes maps on the CPU into plain Images (no shader, no VRAM canvas). First attempt failed on hardware.
Canvases in linear RAM when VRAM runs out (engine). Unblocks the Gen 2 bake, Tilt, and any bigger render target.
Faster canvas creation and reuse, to cut the screen lag on transitions.
Chip music on a second thread, so map and battle music plays without the pre-render step.
Online features through LÖVE Potion's https: route HostShell.httpGet/httpDownload through it for the mod index, mod downloads and the update check.
C-stick (irrstInit).
Bottom screen.

🔍 Debugging on hardware

Lua errors: sdmc:/3ds/save/pokemon-love2d/lua-error.log.
Engine start-up failures (a system service, the boot, the no-game screen): sdmc:/gen1_init.txt and sdmc:/gen1_boot_error.txt. These are the only probes left in the build; the per-frame traces used during bring-up are in docs/instrumentation.md, with patches to put them back.
Native crashes: Luma writes sdmc:/luma/dumps/arm11/crash_dump_*.dmp. Read pc/lr from the register dump and resolve them against the release's gen1recomp-<version>-3ds-symbols.elf: arm-none-eabi-addr2line -f -C -e gen1recomp-<version>-3ds-symbols.elf <pc> <lr>.
3dslink does not stream stdout back; read errors from the files above.
Files on the SD are easiest to pull over wifi: netload ftpd.3dsx, then scripts/3ds/mirror_sd.py <3DS-IP>.

📜 License

This repository (patches, overlay, tools, engine changes) is MIT, see LICENSE. gen1recomp is © BOIS CLUB GAMES, LLC, MIT. LÖVE Potion is © Serena S. Postelnek & Logan Hickok-Dickson, MIT (engine/LICENSE.md). No Nintendo or Game Freak assets, ROMs or firmware are included — bring your own cartridge.

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