Status

Gecko is still in development. While many games work well, most will likely have varying degrees of visual glitches or will be outright broken. Refer to the screenshot databases to gauge compatiblity:

• GameCube
• Wii

Note: Only NTSC games are tracked. The screenshot service makes a best effort attempt to enter games by pressing random buttons. Just because a game doesn't go ingame, doesn't mean it actually doesn't.

Features

Gecko is developed with homebrew development and reverse engineering in mind, but also aims to provide a faithful and playable experience!

• PowerPC JIT (Cranelift)
• DSP JIT (Cranelift)
• GX vertex decode JIT (Cranelift)
• Starlet HLE
• IPL skip patches for NTSC and PAL
• wgpu based renderer backend
  • Supports all major platforms
• wesl based specialized shader compiler
• JIT and shader cache
• FIFO recorder & player
  • Compatible with Dolphin
• Frame pacing
• Modular audio backend, defaults to cpal
  • Supports mixing audio sinks
  • Supports dumping to .wav files
• MCP server
• Lua scripting system for runtime introspection
• A beautiful yet advanced egui-based debugging UI
• Symbol parsing from ELFs and IDA Pro databases
• IDA Pro loaders for DOL and Apploader
• RenderDoc captures with all sorts of debug markers
• ISO and RVZ support; also supports either packed as a ZIP
• Included multitool, supports:
  • IPL decode/encode
  • SYSCONF decode/encode
  • setting.txt decode/encode
  • DVD filesystem extraction
  • Disassembler for PPC and DSP
• Various built-in diagnostics for JIT and GX
• Support for web browser
  • incl. debugging capabilities

There is currently no way to save games for GameCube. Wii save games are supported naturally via NAND.

Usage

Prebuilt releases (including debug builds) can be downloaded here. GameCube and Wii require system files to use the emulator, please refer to the "Required Files" chapter. Minimal commands to launch a game:

# Launch a GameCube game
./tinyapp --ipl IPL.decoded.bin --dsp dsp_rom.bin --coef dsp_coef.bin --skip-ipl --dvd YourGame.rvz

# Launch a Wii game
./tinyapp --dsp dsp_rom.bin --coef dsp_coef.bin --dvd YourGame.rvz

A more modern and friendly experience is provided via gecko (short preview on YouTube):

It scans the configured GameCube and Wii folders for .iso, .rvz and .zip files. Double-clicking on a row opens a dedicated player window for that game. The decoded GameCube IPL and DSP files are expected to be inside the system folder and must be named exactly as follows:

<gecko exe dir>/
  config.toml                # settings
  cache/library.bin          # cached library
  system/                    # system file folder (!)
    IPL.bin                  # GameCube only
    dsp_rom.bin              # GameCube and Wii
    dsp_coef.bin             # GameCube and Wii
  fs/                        # Wii NAND, auto-generated if missing (or drop in a Dolphin/real dump)

Controls

Keybindings are currently hardcoded!

GameCube

Key	Action
Arrow keys	Main stick
I K J L	D-pad (up/down/left/right)
X	A
Z	B
C	X
V	Y
Enter	Start
A	L
S	R
D	Z

Wii

Wiimote:

Input	Action
Mouse movement	IR pointer
Left mouse	A
Right mouse	B
Arrow keys	D-pad
1	1
2	2
Home	Home
-	Minus
=	Plus
Left Shift	Shake (motion)

Nunchuk:

Key	Action
W S A D	Analog stick
Q	Z
E	C

Global

Key	Action
Space	Start emulation from the splash screen (--wait flag)
F10	Trigger a RenderDoc capture (requires renderdoc-capture feature)
F11	Screenshot the full window
F12	Screenshot the emulated framebuffer only

Projects

This is a table of the main projects. Refer to crates/ to find out about all available projects.

Crate	Description
app	End-user library browser (binary name gecko): iced-based game list, double-click to play, per-game player window
tinyapp	Lightweight emulator application with an egui/wgpu GUI, optional Lua scripting
debugger	Interactive GUI debugger built on egui with rendering support, hooks and scripting capabilities
web	WebAssembly build of the emulator for browser deployment via wasm-bindgen, with optional debug UI
multitool	CLI utility for analyzing, disassembling and extracting GC/Wii binaries/images (DOL, IPL, ISO/RVZ) with support for PPC and DSP
fifoplayer	Plays a recorded .dff fifo log. Supports replays generated from Dolphin and Gecko's debugger

Building

git submodule init && git submodule update

cargo build -p gecko-app --release                               # game launcher (binary: gecko)
cargo build -p tinyapp --release                                 # tinyapp
cargo build -p debugger --release                                # debugger
cargo build -p multitool --release                               # multitool
cargo build -p fifoplayer --release                              # fifo player
wasm-pack build crates/web --target web --out-dir pkg --release  # web version

Release builds compile out all tracing output (the gecko crate pins tracing with release_max_level_off), so --release binaries are silent. Build with --profile dev if you want log messages.

Features

Features below are listed based on the frontend crate that supports them. Most of them are simply forwarded into the core gecko and backend-wgpu crates, so the underlying flag of the same name is what actually toggles the behavior. For exact build invocations refer to the GitHub CI actions file.

tinyapp

Flag	Default	Description
fps-counter	on	Emulator-core driven FPS counter (forwards gecko/fps-counter).
scripting	off	Enables Lua scripting support and the --script CLI option (pulls in gecko/hooks + the scripting crate).
scripting-mut-traps	off	Implies scripting: lets scripted hooks re-register themselves at runtime (gecko/hooks-mut-traps).
audio-wav-dump	off	Forwards gecko/audio-wav-dump: write all emulated audio to a .wav sink while running.
renderdoc-capture	off	Forwards backend-wgpu/renderdoc-capture: load the RenderDoc in-app API and emit debug markers.
jit-stats	off	Forwards gecko/jit-stats: per-block PPC JIT stats, block-frequency CSV dumps and more.
gx-stats	off	Forwards gecko/gx-stats: GX submission and draw-call counters surfaced by the core.
profile	off	Forwards gecko/profile: in-process profiler (Windows-only kernel IP sampler).
hotpath	off	Compiles hotpath::measure instrumentation into the core and the wgpu backend; reports on shutdown.
hotpath-alloc	off	Implies hotpath: swaps the global allocator for a counting allocator that attributes allocs to hot functions.
hotpath-cpu	off	Implies hotpath: samples CPU time per measured function via hotpath/hotpath-cpu.
hotpath-tui	off	Implies hotpath: renders the live hotpath TUI instead of dumping a report on exit.

debugger

debugger always builds with gecko/hooks, gecko/audio-wav-dump, image/symbols (ELF/IDA symbol parsing), and the full scripting crate enabled.

Flag	Default	Description
scripting-mut-traps	off	Same as in tinyapp: re-registerable scripted hooks (gecko/hooks-mut-traps + scripting/hooks-mut-traps).
renderdoc-capture	off	Forwards backend-wgpu/renderdoc-capture. With this enabled, F10 triggers a RenderDoc capture of the next frame.

gecko

Flag	Default	Description
jit	on	Cranelift-backed JIT for Gekko, DSP, and GX vertex decode. Without it the core falls back to interpreters.
hooks	off	Memory/instruction trap hook surface used by scripting, the debugger, and tooling like dsptestrunner.
hooks-mut-traps	off	Implies hooks: allows hooks to mutate trap state.
audio-wav-dump	off	Compiles the hound-backed .wav audio sink.
fps-counter	off	Compiles the core FPS counter for more accurate measurements.
jit-stats	off	Implies jit: per-block JIT hit counts, idle-skip stats, CSV dumps (pulls in backtrace).
gx-stats	off	GX command-processor / BP / XF submission counters.
vtx-jit-validate	off	Implies jit + gx-stats. Runs both the GX vertex JIT and interpreter for every draw and reports drift between them.
profile	off	Per-block PPC/DSP heatmap profiler; on Windows it also enables a kernel-IP sampler via windows-sys.
rendersink-blackbox	off	Wraps EmptyRenderSink::exec in std::hint::black_box. Useful for benchmarking.
hotpath	off	Compiles hotpath::measure instrumentation across the core hot loops.

backend-wgpu

Flag	Default	Description
renderdoc-capture	off	Pulls in the renderdoc crate and enables the in-app capture API + debug markers.
hotpath	off	Instruments the wgpu sink (incl. crossbeam channels) for hotpath reporting.

web

Flag	Default	Description
debug	off	Bundles the in-browser debugger UI (pulls in dbglib and egui-phosphor). Enabled for the /dbg build.

tinybench

Flag	Default	Description
(default)	—	Forwards gecko/rendersink-blackbox so the renderless benchmark loop doesn't get optimized away.
jit-stats	off	Forwards gecko/jit-stats for benchmarking.

Required files

Gecko does not ship any system files.

Reference SHA-256 hashes (these are the files the project is developed against):

File	SHA-256
IPL.bin (NTSC, encoded)	7228bd8f0171008e71c48788eef5e0fd5abce8ef85f1d00327c6f3368113d2a5
IPL.decoded.bin (NTSC)	31e9aa82d972a423d9b7ea7bdbdcff0aff86c3ed953600ca841fe24f3f577051
PAL_IPL.bin (PAL, encoded)	a5fd3ab0ed3d63ad365990cbf522f9f175e01d3b37e5f30a8e5a103cbbc749fd
PAL_IPL.decoded.bin (PAL)	011b66ce68d8dcb4f37460fcb322215bcda7df79072aeca22fdc690499deabac
dsp_rom.bin	49d987ee1eab29a157425b82d54516957a81e1bac247c8834e494642605c3e8c
dsp_coef.bin	d7741279c2e8ec5c5fb318f8fbdd6de6bf583520d288e836a5383233a4238179

GameCube

• IPL (NTSC and PAL tested)
• DSP IROM
• DSP coefficient ROM

If you only have an encoded IPL, decode it first with multitool:

multitool ipl --action decode private/IPL.bin private/IPL.decoded.bin

Wii

A NAND is generated on boot whenever fs/ is missing. The folder can be overriden using the GECKO_FS_ROOT environment variable.

# optional!
GECKO_FS_ROOT=/path/to/dolphin-nand tinyapp --dvd wii_game.rvz # ... and other arguments

Usage

Example invocations:

multitool ipl --action decode ipl.encoded.bin ipl.decoded.bin
multitool sysconf --action decode fs/shared2/sys/SYSCONF SYSCONF.txt  # edit, then re-encode
multitool sysconf --action encode SYSCONF.txt fs/shared2/sys/SYSCONF
multitool setting --action decode fs/title/00000001/00000002/data/setting.txt setting.decoded
multitool setting --action encode setting.decoded fs/title/00000001/00000002/data/setting.txt
multitool dvd --extract game.rvz

tinyapp --dol homebrew.dol  # may also require a DSP depending on the DOL
tinyapp --dvd game.iso --ipl ipl.decoded.bin --dsp dsp_rom.bin --coef dsp_coef.bin --skip-ipl

debugger --dvd game.rvz --ipl ipl.decoded.bin --dsp dsp_rom.bin --coef dsp_coef.bin --script example.lua

The CLI options are largely the same across the sub projects (such as the debugger). For more options, see --help.

Why?

Why do we get a new Wii emulator? Well, it all started a few years ago. I wanted to do something nostalgic and as a kid I spent countless hour in this one Wii game called Final Fantasy Crystal Chronicals: The Crystal Bearers. It wasn't a well received game but I loved it so much, I chose my online persona "Layle" after the main protagonist. I figured it would be cool to spend some years learning about emulation development with the goal to eventually run the game in my own emulator!

Sister Projects

Gecko is being developed alongside other amazing emulators that shaped how Gecko came to be. Without them, Gecko wouldn't exist!

• lazuli by vxpm
• solstice by hazelwiss
• beanwii by zayd

Besides these "sister projects", Dolphin has also been a major contributor in many ways.