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.C4G file extension

To open .C4G files on Windows, install/locate a Clonk/OpenClonk installation that includes the group tool (often named c4group.exe).

To open a .c4g file, use the Clonk/OpenClonk group-file tool (c4group) or a Clonk/OpenClonk installation that includes it. A .c4g file is usually a packed container of game resources, so “opening” often means extracting or listing its contents.

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Last updated: April 29, 2026 · Reviewed by Julian Stricker

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .C4G files

Use these platform-specific instructions to open .C4G files safely.

Windows

  1. Install/locate a Clonk/OpenClonk installation that includes the group tool (often named c4group.exe).
  2. Use the c4group tool to list or extract the .c4g contents (for example by running c4group.exe from the command line with appropriate options as documented by OpenClonk).
  3. If you only want to “use” the file in-game, put the .c4g where your Clonk/OpenClonk setup expects game data and launch the game (exact location/usage depends on the specific Clonk/OpenClonk setup).
Full Windows guide

Mac

  1. There is no commonly documented native macOS workflow in the provided sources; if you need to inspect or extract the file, transfer it to a Windows or Linux machine with the OpenClonk c4group tool available.
  2. If you are using a Clonk/OpenClonk build on macOS that includes a compatible c4group tool, use that tool to list/extract the container as described in OpenClonk documentation.
Full Mac guide

Linux

  1. Install/locate OpenClonk tools that provide the c4group command.
  2. Run c4group against the .c4g file to list or extract its contents (use the OpenClonk command-line documentation for supported parameters).
  3. If your desktop environment recognizes the file type via shared MIME-info, you may also be able to right-click the file and choose an associated Clonk/OpenClonk tool, if configured.
Full Linux guide

iOS

  1. iOS typically cannot work with .c4g containers directly; transfer the file to a desktop (Windows/Linux) and use the OpenClonk c4group tool to inspect or extract it.
Full iOS guide

Android

  1. Android typically cannot work with .c4g containers directly; transfer the file to a desktop (Windows/Linux) and use the OpenClonk c4group tool to inspect or extract it.
Full Android guide

Security notes

  • .c4g files are compressed containers (group files). Treat them like archives: extracting them can create many files, and their contents may include scripts or game logic intended for the Clonk/OpenClonk engine.
  • Only open or extract .c4g files from sources you trust; a malicious or malformed container could exploit vulnerabilities in tools that parse the format (including c4group or game engines).
  • Be cautious when extracting into important folders: group files can contain nested paths and many resources, so extract into an empty, dedicated directory first.

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Can't open this file?

These are the most common causes and fixes when .C4G files fail to open.

Common reasons

  • The file opens in the wrong app or shows as an unknown file type
  • c4group cannot read the .c4g (errors, missing contents, or extraction fails)
  • I expected to “play” it, but it looks like an archive

Fix steps

  1. Open it with the OpenClonk/Clonk group tool (c4group / c4group.exe) instead of trying a generic editor.
  2. On Linux, ensure your system recognizes it via the shared MIME-info mechanism and set the default app association if needed.

OS-specific troubleshooting

What is a .C4G file?

.c4g is a Clonk/OpenClonk group file: a compressed container used to bundle game data (resources, scripts/config, and other assets) for the Clonk game family. In OpenClonk documentation, these are referred to as “group files” that store game data in a compressed form. On Linux desktops, file typing may come from the freedesktop.org shared MIME-info database mechanism and is commonly identified as application/vnd.clonk.c4group.

Background

The Clonk game series uses “group files” as a packaging format for its content. These group files are commonly found with extensions like .c4g (as well as related group-based extensions such as .c4f and .c4d mentioned in Clonk descriptions). In practice, a .c4g behaves like a game-data archive: it’s meant to be consumed by the game engine and its tooling rather than edited directly with a generic editor.

In the OpenClonk ecosystem, group files are a standard way to ship and organize scenarios, objects, definitions, and other assets. The official OpenClonk documentation describes game data as stored in compressed group files and provides command-line tooling (c4group / c4group.exe) to work with these containers.

Because .c4g files are containers, what you can do with them depends on your goal: players typically just place them where the game can load them, while modders or developers often use c4group to list contents or extract files for inspection and editing.

Common MIME types: application/vnd.clonk.c4group

Further reading

Authoritative resources for more details on the .C4G format.

Common .C4G issues

The file opens in the wrong app or shows as an unknown file type

.c4g is a niche game-data container; many systems won’t have an associated app by default, and Linux association depends on MIME database entries and desktop configuration.

  1. Open it with the OpenClonk/Clonk group tool (c4group / c4group.exe) instead of trying a generic editor.
  2. On Linux, ensure your system recognizes it via the shared MIME-info mechanism and set the default app association if needed.

c4group cannot read the .c4g (errors, missing contents, or extraction fails)

This can happen if the file is incomplete/corrupted or not actually a valid Clonk/OpenClonk group file despite the extension.

  1. Re-download or re-copy the file to rule out transfer corruption (especially if it came from the internet or removable media).
  2. Try listing the archive contents first with c4group; if listing fails, the container is likely damaged or not a real group file.
  3. Confirm the file’s origin is Clonk/OpenClonk-related; if not, the extension may be misleading.

I expected to “play” it, but it looks like an archive

.c4g is usually a container of game assets; it’s often meant to be loaded by the Clonk/OpenClonk engine rather than opened as a document.

  1. If you have the game, try using it from within Clonk/OpenClonk (how depends on the specific game version/content).
  2. If you are modding or inspecting content, use c4group to extract the files, then open individual extracted resources with appropriate editors.

FAQ

What program opens a .c4g file?

.c4g is associated with Clonk/OpenClonk group files. The commonly documented way to work with it is the OpenClonk group tool (c4group / c4group.exe) and Clonk/OpenClonk installations that support group files.

Is .c4g just a renamed ZIP file?

In OpenClonk documentation it is described as a compressed “group file” container, but it should be handled with the Clonk/OpenClonk tooling (c4group). Renaming it to .zip is not a reliable or supported way to open it.

What does the MIME type application/vnd.clonk.c4group mean?

It’s an identification label used by systems and desktop environments to recognize the file as a Clonk group file. On Linux, such mappings are typically managed via the freedesktop.org shared MIME-info database mechanism.

Can I open .c4g on my phone?

Typically not in a practical way. The common workflow is to transfer it to a desktop system and use c4group to list/extract contents or to load it via the Clonk/OpenClonk engine.

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