Jet Force Gemini: Recompiled

Playable PC port of Jet Force Gemini (N64, US) for Windows Linux, & Steam Deck, made by static recompilation. No emulator: the game's code is translated from your ROM and compiled for your PC.

Roadmap:

Linux players on 1.2.x: download this release by hand once. The repository was renamed and the old update check can't see the new name; from 1.3 on, it works as usual.

No game code or assets are included. You need your own ROM.

Contents: ROM · Features · Modding · Steam Deck · Keys · Build from source · Reporting bugs · How it works · AI disclosure · Legal · Credits · Roadmap · Known issues

ROM

Jet Force Gemini US, .z64 format, SHA-1 493ced9008dbe932d6e91179b68e8630cf23a023.

Features

4K textures The official HD texture pack: every texture upscaled to up to 4K. It installs and updates from the launcher, and switches in-game with F6. Get it at JetForceGemini-HD_TexturePack (more about the pack).	Modern controls Dual-stick or mouse and keyboard, with over-the-shoulder aim and a centered reticle, sprint, and Floyd missions you can fly with the mouse.
Modding 20+ official mods, one click each in the launcher's Get Mods page: a minimap, new weapons, a dodge, a kill feed, custom enemies and more (JFG-Mods). Make your own levels, planets and galaxies with JFG-Studio; see Modding.	Real-time lighting coming in 1.4 A first look at modern lighting for the next release.

And more

• 10+ languages (English, French, German, Spanish, Japanese, Swedish and more).
• Display frame rate up to 240 Hz, or your monitor's refresh rate, for smoother motion.
• Widescreen, ambient occlusion and bloom, and no LOD pop-in.
• Auto Save, Unlimited Continues, and Tribals that stay rescued.
• Profiles: the original game or a modern setup in one click.
• Full controller support in the menus, launcher and tools; rebindable controls and Rumble Pak.
• Skip cutscenes, gore options and a weapons editor.
• F10 tools: cheats, level warp and an items editor. Fly camera for screenshots (F7).

Modding

Mods are .nrm files in bin/mods/, turned on and off and ordered in the Mods tab of the settings menu. A mod can add planets and whole galaxies to the planet map, new levels, reskinned enemies, its own music, Lua scripts and weapon tuning, change the game's own levels, or patch the game's code.

• The JFG Modding Wiki: how to make mods, with tutorials, the API's status (built, partial, planned) and the pack formats.
• JFG-Studio: a level and modpack editor. Place squads, doors, keys, pickups and exits on your own geometry, set up planets and galaxies, add triggers, scripts and music, then build the pack and play it with one button. It reads your own ROM; nothing from the game is in what it makes.
• jfg64: a Blender add-on for modelling level geometry for Studio.
• Code mods are built with N64Recomp's RecompModTool against the symbols in JFGRecompSyms, with the port's API in mod_api/jfg_api.h.

Texture packs

• Texture dumping, all in one folder or one folder per level.
• A pack is a folder in bin/texture_packs/<name> or a packed .rtz file (a zip with rt64.json at its root) in bin/texture_packs/, picked from a list and switched in-game with F6. A .rtz pack can also go in bin/mods/: it is then loaded as a mod, and can be switched on and off and reordered in the Mods tab of the settings menu.
• To make your own texture pack, see docs/TEXTURE_PACKS.md.
• How the port gives levels and mods more memory than the N64 had: docs/MEMORY.md.

Steam Deck

Use the Linux AppImage, and always start the game through Steam, in Desktop Mode too:

1. In Desktop Mode, make the AppImage executable (right-click it, Properties > Permissions), then add it to Steam (right-click > Add to Steam, or "Add a Non-Steam Game" in Steam).
2. Start it from your Steam library, in Game Mode or Desktop Mode.
3. Choose your ROM the first time in Desktop Mode: Game Mode may have no file picker. Or write its path in ~/.local/share/JetForceGeminiRecompiled/jfg_launcher.txt as rom=/home/deck/path/to/baserom.us.z64.

Keep Mouse and Keyboard Controls (settings menu, Controls tab) Off on the Deck. The Modern profiles turn it on, so set it back to Off after choosing one, or turn on Keep My Controls (Profiles tab) first.

Why: started from the file manager, Steam turns the Deck's controls into a keyboard and mouse as well as a controller, so every press counts twice (Start opens the settings menu, and menu moves skip a button). With Mouse and Keyboard Controls on, the touchscreen and trackpads act as a mouse that aims and fires, and firing can stay stuck after you close the settings menu.

Keys

Key	Action
Select / Esc	Settings menu
F10	Tools toolbar (Alt switches between the toolbar and the game)
F9	Debug window
F5 / F6	Back to the title screen / next texture pack
F7	Fly camera
F11 / Alt+Enter	Fullscreen

Build from source and run

Save your rom as baserom.us.z64 in this folder.

Windows (10/11, Direct3D 12 GPU): install Visual Studio 2022 (Desktop development with C++, plus C++ Clang tools), Git and Python 3. Run build_windows.bat (the first build takes 10-40 minutes, about 15 GB), then run_windows.bat.

Linux (Vulkan GPU). The release files run on Ubuntu 22.04 or newer, Debian 12 or newer, current Fedora and SteamOS 3: the AppImage (on a Steam Deck: make it executable, then "Add a Non-Steam Game"; saves go to ~/.local/share/JetForceGeminiRecompiled) or the portable .tar.gz (saves stay in its folder). Older systems (Ubuntu 20.04, Debian 11) are not supported. The update check and the HD pack download need curl, and the Open Folder buttons need xdg-open (xdg-utils).

To build it yourself, install the packages for your system, then run ./build_linux.sh && ./run_linux.sh. The build needs clang 15 or newer and a recent CMake, so on Ubuntu 22.04 and Debian 12 use the release files instead (or the build container, see tools/package_release.sh). On SteamOS, use the AppImage.

Ubuntu 24.04 or newer, Debian 13 or newer:

sudo apt install git cmake ninja-build clang lld python3 libsdl2-dev libvulkan-dev libgtk-3-dev libdbus-1-dev libfreetype-dev zlib1g curl

Fedora:

sudo dnf install git cmake ninja-build clang lld python3 SDL2-devel vulkan-loader-devel gtk3-devel dbus-devel freetype-devel libatomic-static zlib curl

The game ends up in bin, together with its saves and settings. The build also creates empty bin/mods and bin/texture_packs folders for mods and texture packs (see docs/TEXTURE_PACKS.md); anything already in them is kept. The build itself happens in this folder (lib, build-tools, build-windows / build-linux, RecompiledFuncs), none of which is committed. Keep bin private, because it holds a copy of the ROM.

Reporting bugs

Report bugs on the Issues page. Check first whether it is already reported there or listed in Known issues.

Please include:

• Your version. It's shown in the launcher (for example 1.2.1). If you built the game yourself, the commit.
• What happened and what you expected. Steps to make it happen again, if you know them.
• Where. The level and roughly where in it (turn on Show Level in the settings menu's General tab to put the level number on screen), or the menu or cutscene.
• Your setup. Windows, Linux or Steam Deck, your GPU, and your monitor's refresh rate.
• Your settings, if they could matter: the profile, Display Frame Rate and Game Frame Rate (Graphics tab), widescreen, and the texture pack, if any.
• A screenshot or video, for anything visual.
• Logs, if the game crashed or stopped with an error: crash.log, jfg_error.log and jfg_memory.log, whichever exist. Settings files help too: jfg_port_options.txt and graphics.json.

Where those files are:

Game	Folder
Windows zip	next to JetForceGeminiRecompiled.exe
Linux AppImage and Steam Deck	~/.local/share/JetForceGeminiRecompiled
Linux portable (tar.gz)	the game folder
Built yourself	bin

Do not attach your ROM, or any other file from those folders beyond the ones above.

How it works

N64Recomp translates the game's code into C, which is compiled for your PC. N64ModernRuntime stands in for the N64's operating system and RT64 draws the game. The port is built on cyscott/dkr-recomp, and its own code is in src/jfg/. The three libraries are submodules in lib/ pinned to the port's forks (branch jfg).

AI disclosure

This project is AI-assisted and directed by a software developer who reviews the output and tests it by hand.

Legal

Jet Force Gemini and its logos belong to their rights holders. This project is not affiliated with or endorsed by them. Do not share the ROM or anything generated from it. The code is licensed under GPL v3 (see LICENSE).

Credits

• The Jet Force Gemini decompilation project
• cyscott/dkr-recomp and the Diddy Kong Racing decompilation
• N64Recomp, N64ModernRuntime, RT64 and their contributors