Overview

GnGeo runs NeoGeo ROM sets identified by their MAME names, such as mslug for Metal Slug. It supports AES emulation and save states, and offers home, arcade, and unibios system modes. The command line gives experienced users fine control, while configuration files can hold general or per-game settings.

Setup is a meaningful trade-off. GnGeo requires SDL 1.2.x, libz, and a NeoGeo BIOS; games must be ZIP files, while the BIOS must not be. By default, it looks for both under $prefix/share/gngeo/. The documented source build uses ./configure, make, and make install. NASM 0.98 is optional for i386 assembly optimization.

Key features

Display, sound, and controls

Fullscreen, resolution scaling, interpolation, raster interrupts, selectable blitters, and visual effects give users control over how games are presented. Sound settings include sample rate, and joystick support is paired with per-player controls and configurable hotkeys. This breadth suits users willing to tune settings; it is less compelling for anyone expecting a polished, self-contained desktop setup.

Emulation and frontends

GnGeo can use Cyclone, Starscream, or Gen68k for its 68k core, and DrZ80, Raze, or MAME Z80 for its Z80 core, with defaults depending on the target. The README also describes GGF, XGngeo, and gngeogui frontends, including game previews and configuration options. These provide alternatives to command-line use, though the project’s core workflow remains shaped by its configuration and dependency requirements.

Pricing

GnGeo — 0.00 USD per free. The software is free and open source, with no free trial. Its price does not remove the setup costs: users still need SDL 1.2.x, libz, and a NeoGeo BIOS. The README says the original code is GPLv2 with a special linking exception, but forbids commercial use of GnGeo as a whole because of included code and licensing. That restriction rules it out for commercial deployment.

Platforms

GnGeo targets Linux, with the project also describing possible support for other Unix systems. Linux users prepared to manage older dependencies are the natural audience; those on other platforms should not treat Unix support as a confirmed substitute for a supported release.

Who it's for

Choose GnGeo if you want a free Linux NeoGeo emulator with configurable system modes, input, display, and per-game settings, and you can supply the BIOS and game files yourself. Look elsewhere if you need commercial use, a broader confirmed platform range, or a packaged release: the repository has no releases, so the documented source build is the practical route.

Pros and cons

Pros: Broad command-line and configuration-file control, including per-game settings, helps users tailor games without being limited to one global setup.
Pros: Multiple 68k and Z80 core options, save states, and AES emulation offer useful flexibility for a Linux-focused emulator.
Cons: SDL 1.2.x, libz, and a separately supplied NeoGeo BIOS add setup work and dependency-management overhead.
Cons: No repository releases means users rely on the source-build process rather than a published release package.
Cons: The stated ban on commercial use of GnGeo as a whole makes it unsuitable for commercial deployment.

Alternatives

Compare Neo Geo Emulators for other options. Pick NeoDS if its free, non-commercial emulator code better fits your use. NeoCD/SDL is a free Linux and Windows option, but selling is not allowed, reuse and technical knowledge are limited to non-commercial purposes, and it requires an original NeoGeo CD BIOS.

Choose NeoRAGEx if you need a free Windows emulator; games and BIOS are not included. Virtual Jaguar offers a free open-source emulator core across Android, iOS, Linux, macOS, web, and Windows, but requires a libretro frontend such as RetroArch. Geolith is another free option for Linux, macOS, and Windows.

GxGeo is another free alternative. Lynx.emu is a paid Android, iOS, and Linux option at 2.99 USD per once; it is open source and requires users to supply ROMs. NeoBox is a paid Mac-only option at 14.99 USD per once, requires macOS 14 or later, and also requires users to provide ROMs and BIOS files.

Verdict

GnGeo is a strong fit for technically capable Linux users who want a free, configurable way to run NeoGeo ROMs and are prepared to build and supply the required files. Its main appeal is the depth of its emulation and configuration options; its dated dependencies, lack of releases, and commercial-use prohibition are clear reasons to choose another emulator when convenience or commercial deployment matters.

	Geolith	GnGeo
Free plan	No	Yes
Free trial	No	No
Paid from	—	Free
Open source	No	No
Platforms	Linux, macOS, Windows	Linux
AES emulation	Yes	Yes
MVS emulation	Yes	—
Neo Geo CD support	Yes	—
Supported platforms	Linux, macOS, BSD, Windows	Linux
Save states	—	Yes

Geolith vs GnGeo

Geolith

GnGeo