Freedom251 › Neo Geo Emulators
Geolith
What Geolith is
Geolith is a free emulator for Neo Geo AES, MVS, CD, and CDZ systems, available for Linux, macOS, and Windows. Its project states compatibility with commercially released AES, MVS, and CD games. Cartridge systems use TerraOnion .NEO files; CD systems accept .bin/.cue and can optionally use .chd images. BIOS files from a recent MAME set are required, with the required archives depending on the system. Geolith emulates CPUs at instruction-level granularity and synchronizes them with one another and the video and sound systems. Video-event timing is best effort, and cycle-accurate rendering is a longer-term goal; the project describes games as playable with minor differences from hardware and no known major bugs. Options include AES, MVS, or Universe BIOS mode, region, free play, memory-card settings, palette, and aspect ratio. Supported inputs include Neo Geo joysticks, Mahjong Controller, a four-player extension board, V-Liner, and the Irritating Maze trackball. Dedicated JAMMA PCB systems and PAL mode are unsupported, and an early Stakes Winner prototype cannot currently be emulated.
Who it suits
Geolith suits players looking for a Neo Geo AES, MVS, or CD emulator on Linux, macOS, or Windows. It also supports specialized controllers and multiple system and display settings.
What it does well
- Free plan.
- Supports AES, MVS, CD, and CDZ systems.
- Accepts .NEO, .bin/.cue, and optional .chd formats.
- Offers multiple BIOS modes and display settings.
What to know first
- Requires BIOS files from a recent MAME set.
- No support for dedicated JAMMA PCB systems or PAL mode.
- One early Stakes Winner prototype cannot be emulated.
Getting started
- Open the Geolith project page at https://gitlab.com/jgemu/geolith.
- Choose a supported platform: Linux, macOS, BSD, or Windows.
- Provide BIOS files from a recent MAME set, using the archives required for your system.
- Use .NEO files for cartridge systems, or .bin/.cue and optionally .chd images for CD systems.
- Select the system, BIOS mode, region, and other available settings.
Verdict
Geolith covers several Neo Geo systems and supports a range of game formats and input devices. Buyers should note its BIOS requirement and the limits on JAMMA PCB systems, PAL mode, and one prototype.
Questions
Is Geolith free?
Yes. Geolith is listed as free, with a free plan and no free trial.
Which platforms does Geolith support?
The listed platforms are Linux, macOS, BSD, and Windows.
Which Neo Geo systems does it emulate?
Geolith is for Neo Geo AES, MVS, CD, and CDZ systems. The project states compatibility with commercially released AES, MVS, and CD games.
What game files and BIOS does Geolith require?
Cartridge systems support TerraOnion .NEO files. CD systems support .bin/.cue and optionally .chd images; BIOS files from a recent MAME set are required, with archives varying by system.
Is Geolith open source?
The README identifies Geolith as BSD-3-Clause licensed.
Who is credited with Geolith?
The README credits Rupert Carmichael and Romain Tisserand for Geolith copyright.
Facts from Geolith's own pages
- Accuracy
- The emulator synchronizes its CPUs with video and sound components, while video event timing is described as best effort and cycle-accurate rendering remains a longer-term goal. · gitlab.com, 29 Sept 2026
- Accuracy caveat
- Video events use best-effort timing; the project says games are playable with minor differences from real hardware and no known major bugs. · gitlab.com, 30 Sept 2026
- API integration
- Geolith is written for The Jolly Good API and requires that API's header files to compile. · gitlab.com, 29 Sept 2026
- BIOS requirement
- BIOS files from a recent MAME set are required. · gitlab.com, 30 Sept 2026
- Build platforms
- The README gives build instructions for Linux, macOS, BSD, and Windows using MSYS2. · gitlab.com, 30 Sept 2026
- Cartridge format
- Cartridge systems support TerraOnion’s .NEO file format only. · gitlab.com, 30 Sept 2026
- Compatibility
- The project states that Geolith is compatible with 100% of commercially released Neo Geo AES, MVS, and CD libraries. · gitlab.com, 30 Sept 2026
- Disc formats
- CD systems support .bin/.cue and, optionally, .chd disc images. · gitlab.com, 30 Sept 2026
- Emulation detail
- The CPUs are emulated at instruction-level granularity and synchronized with each other, the LSPC video system, and YM2610 sound. · gitlab.com, 30 Sept 2026
- Founded
- 2022 · gitlab.com, 23 Sept 2026
- Framework
- Geolith was written for The Jolly Good API and can also be used in multi-emulator frameworks or standalone binaries. · gitlab.com, 30 Sept 2026
- Game formats
- Cartridge systems support TerraOnion .NEO files, while CD systems support .bin/.cue and optionally .chd disc images. · gitlab.com, 29 Sept 2026
- Input devices
- Supported input devices include Neo Geo joysticks, the Mahjong controller, a four-player extension board, V-Liner, and the Irritating Maze trackball. · gitlab.com, 30 Sept 2026
- Known limits
- Dedicated JAMMA PCB systems and PAL mode are not supported, and an early Stakes Winner prototype cannot currently be emulated due to missing data. · gitlab.com, 29 Sept 2026
- Latest changelog entry
- Version 0.4.2 lists a fix for an LSPC state leak when switching between CD and cartridge games and support for The Jolly Good API 2.0.0. · gitlab.com, 29 Sept 2026
- License
- The README identifies Geolith as BSD-3-Clause licensed. · gitlab.com, 30 Sept 2026
- Maintainer
- The README credits Rupert Carmichael with Geolith copyright from 2022 through 2026. · gitlab.com, 29 Sept 2026
- Maker
- The README credits Rupert Carmichael and Romain Tisserand for Geolith copyright. · gitlab.com, 30 Sept 2026
- Notable limits
- Dedicated JAMMA PCB systems and PAL mode are not currently supported, and an early Stakes Winner prototype cannot yet be emulated. · gitlab.com, 30 Sept 2026
- Project date
- The GitLab project page says it was created February 23, 2022. · gitlab.com, 30 Sept 2026
- Project purpose
- Jolly Good Emulation describes itself as a preservation-oriented emulation project focused on reusability, simplicity, and readable code. · jgemu.gitlab.io, 29 Sept 2026
- Purpose
- Geolith is a highly accurate emulator for the Neo Geo AES, MVS, CD, and CDZ. · gitlab.com, 30 Sept 2026
- System settings
- Settings allow selection of AES, MVS, or Universe BIOS mode, CD system, region, free play, memory card options, palette, and aspect ratio. · gitlab.com, 29 Sept 2026
- What it does
- Geolith is a highly accurate emulator for the Neo Geo AES, MVS, CD, and CDZ. · gitlab.com, 29 Sept 2026
Where Geolith stands on Freedom251
- Neo Geo Emulators#1 of 18