Gearboy

GAME BOY & GAME BOY COLOR EMULATOR CORE

Gearboy

Gearboy — an open-source Game Boy / Game Boy Color / Super Game Boy emulator provided as a standalone application and as a Libretro core (gearboy_libretro).

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Gearboy emulator screenshot.

Game Boy & Game Boy ColorPRIMARY SYSTEM

History documentedPROJECT BEGAN

Open sourcePROJECT MODEL

WHY IT MATTERS

Why pick Gearboy?

Gearboy focuses on accurate Game Boy and Game Boy Color emulation while offering modern features (save states, run-ahead, rewind) and an extensive debugger and development tools. It is available both as a standalone desktop application and as a libretro core usable from RetroArch and other libretro frontends.

BEST FOR

Best for

Users who want a modern, actively maintained GB/GBC core for RetroArch or a feature-rich standalone emulator with debugging tools, SGB support, controller and link-cable options, and run-ahead/rewind functionality.

The people behind Gearboy

History & status

Gearboy is an open-source C++ Game Boy, Game Boy Color and Super Game Boy emulator maintained upstream in a public repository and distributed both as a standalone app and as a libretro core. The project is actively developed and publishes releases and build artifacts on its GitHub repository. Libretro documentation lists Gearboy in its core catalog and links to the libretro core documentation; historically RetroArch used Gearboy as one of its GB/GBC cores, and the libretro project contains an archived copy of the core metadata. The upstream GitHub repository contains release binaries and platform packaging (Windows zips, macOS Homebrew cask instructions, Linux packages), and the code is licensed under GPLv3. Because development and release activity are maintained on the project’s GitHub and libretro pages, check those sources for the most recent release and build instructions before installing.

What Gearboy supports

Game Boy (DMG)
Game Boy Color (CGB)
Super Game Boy (SGB)
Local two-instance link cable (desktop & libretro)
Run-ahead and rewind
Save states and battery-backed SRAM saves

Download and availability

OFFICIAL DOWNLOADS

Get Gearboy

Official downloads and libretro core information are published from the project's GitHub releases and the Libretro documentation. Use the GitHub Releases page for standalone binaries and the Libretro core downloader (or the libretro buildbot) to obtain gearboy_libretro for RetroArch.

Get Gearboy ↗

DOCUMENTATION

Official documentation

Read the official configuration, compatibility, and troubleshooting material before changing advanced options.

Read official documentation ↗

Broken or missing download? Emulator projects move and official links sometimes change. Please contact Retro Replay so the source can be verified and updated.

Gearboy setup guide

Setup note: Practical setup notes for both standalone Gearboy and the libretro core (gearboy_libretro). This guide focuses on verified steps and precise, practical configuration details rather than generic emulation advice.

1) Choose standalone or RetroArch core: Decide whether you want the standalone Gearboy application (desktop builds for Windows, macOS, Linux, BSD) or the libretro core (gearboy_libretro) to use inside RetroArch or another libretro frontend. The standalone app includes the full debugger, MCP server and other development features; the libretro core is intended for use inside frontends and on many platforms supported by libretro/RetroArch.
2) Downloading standalone Gearboy: Visit the project's GitHub Releases page and download the release appropriate for your platform/architecture (Windows x64/arm64 zips, macOS zips, Linux desktop zips, or platform-specific packages listed there). Windows builds may require Visual C++ redistributable and appropriate OpenGL support; Linux desktop builds may depend on libsdl3. For macOS the repository documents a Homebrew cask command for installation; follow the release notes for any platform-specific prerequisites.
3) Installing the libretro core (gearboy_libretro): Inside RetroArch: use Online Updater → Core Updater and select 'Gearboy' (listed in the Libretro core list). Alternatively, obtain the core binary from the libretro core download page or from a libretro buildbot/archive. Place the core binary (gearboy_libretro.*) in RetroArch's cores directory if installing manually. After installation, start RetroArch, load the core (Load Core → Gearboy), then Load Content to open a ROM.
4) ROMs and Boot ROM (BIOS) handling: Gearboy accepts Game Boy and Game Boy Color ROM files (.gb, .gbc, .dmg) and compressed ZIPs. The core and standalone emulator support optional bootrom (BIOS) files; a boot ROM is not required for most games but is required if you want the console boot sequence. Do not expect any BIOS or commercial game ROMs to be bundled — you must supply them yourself and only use legally obtained files.
5) Core and standalone configuration: In RetroArch, configure the Gearboy core options under Quick Menu → Options (or set them in the retroarch.cfg / core-specific .opt file). Options include model selection (DMG vs CGB), palettes, bootrom enabling, link-cable behavior, and run-ahead. For the standalone app, use the GUI menus or command-line switches; the README documents portable mode, link-cable session parameters, and MCP server options. On desktop platforms, the standalone application supports drag-and-drop ROM loading and a portable mode (use –portable or create a portable.ini file).
6) Link cable / two-instance setup: Standalone: start two desktop instances and use the Link Cable menu to create/join the same session, or launch each instance with –link-cable-join N. Ensure instances run from separate portable data directories to avoid profile conflicts. Libretro: use a frontend that supports multiple instances or the libretro link implementation; check the frontend documentation for connecting two cores/instances.
7) Debugging and development features (standalone): The standalone Gearboy includes a full debugger (disassembler, breakpoints, memory/VRAM viewers, trace logging) and an MCP server for remote/AI-assisted debugging. Consult the project's MCP_README and README for instructions to enable the MCP server (stdio or http transports), debug symbol loading, and trace/logging options.
8) Troubleshooting & compatibility tips: If RetroArch core fails to run, ensure your RetroArch build supports the core architecture and that your platform's libretro core folder is configured correctly. For standalone builds, verify required system libraries (Visual C++ on Windows; libsdl3 on Linux). If you need run-ahead or rewind, enable the feature in the core/frontend settings and check performance on low-power devices. For any runtime errors consult the project's GitHub Issues page and the libretro docs entry for Gearboy for platform-specific notes.

Software reminder: Gearboy is GPLv3-licensed and does not include commercial ROMs or proprietary BIOS files. Obtain ROMs and BIOS files legally and supply them yourself. Check license and usage terms in the repository and in the libretro documentation before redistribution.

Sources and further reading

Detailed guides and tutorials

Explore step-by-step guides for Gearboy as they are published.

Use Gearboy on Android

An Android ARM64 Libretro build exists for Gearboy. Run the core through RetroArch for Android; the standalone desktop download and Android core may have different menus and features.

Emulates: Game Boy.

Verified Android core build ↗ · Browse all Android emulators →