Metin2 client modding intro: .eix and .epk archives explained (EterNexus guide)

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If you want to mod your Metin2 client, the short answer is this: almost everything the client uses (textures, models, maps, interface scripts, item icons) lives inside paired .eix and .epk archives in the pack folder, and EterNexus is the classic community tool for extracting, editing and repacking them. Here is how the EterPack format works, what the extract and repack workflow looks like, what modders usually change, and the risks to know before you touch anything.

What .eix and .epk files actually are

Metin2 does not ship its assets as loose files. It uses a container format called EterPack. Every archive is a pair:

• The .eix file is the index. It stores the list of files inside the archive along with the metadata the client needs: the virtual path where each file should be mapped, its size, and which compression or encryption type was used to store it.
• The .epk file is the content. It is basically a raw blob of file data with no header of its own. On its own it is useless; the client (or a tool) needs the matching .eix to know where each file starts and how to decode it.

The index itself is not plain data either. It is stored as a so called Crypted Object, encrypted with the XTEA algorithm. Once decrypted, the header starts with the FourCC "EPKD", a version field (2 in the classic clients) and the number of files in the pack. The classic client used fixed, publicly known XTEA keys for the index and the content, which is exactly why tools like EterNexus can open official packs at all. The full format including header layout and default keys is documented in the EterPack file format page on Metin2Dev and the related Crypted Object page.

Individual files inside a pack are stored in different ways, identified by a type number in the index:

• Type 0: raw, no compression and no encryption.
• Type 1: compressed with LZO, no encryption.
• Type 2: compressed with LZO and then encrypted with XTEA using the content keys. This is the common case for official packs.
• Higher types exist in newer or modified clients: Panama encryption (type 3), HybridCrypt (types 4 and 5) and Snappy compression with XTEA (type 6).

You do not need to memorize this, but it explains why some tools open certain packs fine and choke on others: private servers often change the XTEA keys or use newer types precisely to keep casual tools out.

Extracting and repacking with EterNexus

EterNexus is a Windows GUI tool (built with Qt and C++) that reads and writes EterPack archives. The original project by christian-roggia is open source under the MIT license, and although the author declared it dead years ago, the source is still on GitHub with community forks keeping it alive.

The basic workflow:

• Back up your client's pack folder in full. Not optional.
• Open EterNexus and load the .eix file of the archive you want (File, then Extract Archive). The tool reads the index, decrypts it, and pulls the matching files out of the .epk into a normal folder.
• Edit whatever you want in the extracted folder with normal tools: image editors for .dds and .tga textures, a text editor for interface Python scripts and .txt data, and specialized tools for .gr2 models.
• Repack the folder into an .eix and .epk pair and drop it back into the pack folder, replacing the originals (which you backed up, right?).

Two practical warnings. First, EterNexus is old and community threads have long reported that it can skip or mangle some files on certain packs, item icons are a common victim, so sanity check the extracted output before assuming you have everything. Second, on a modern private server client the keys or pack types may have been changed and stock EterNexus will produce garbage. In that case look at newer alternatives: PackMakerLite is a popular archiver on the dev forums, and there is a clean, scriptable Python implementation, m2a.py by martysama0134, which is much easier to adapt when keys differ.

What modders typically change

The classic beginner mods are almost all texture and interface work:

• Custom login screens and interface skins (the interface related packs).
• Retextured weapons, armors and mounts by editing the .dds textures next to the .gr2 models.
• Map appearance tweaks through terrain textures and environment settings.
• Item icon replacements.
• Interface behavior changes through the packed Python UI scripts, which is where cosmetic modding turns into real client scripting.

Adding entirely new models or effects requires Granny (.gr2) tooling and deserves its own thread.

The risks, read this part

• Official servers: modifying the official client violates the terms of service. Cosmetic or not, a modified pack can get your account banned, and modern official clients ship anti tamper protection that detects changed archives. Keep client modding to private servers and local setups.
• Malware: the scene is full of precompiled tools and "unpacked client" downloads from forum attachments and file hosts, and a packer tool is an ideal trojan carrier. Prefer open source tools you can read (the MIT licensed EterNexus source and m2a.py qualify) and scan anything precompiled.
• Broken clients: a repack with a wrong key, wrong type or a missing file usually means a crash on startup with no useful error. Keep the original .eix and .epk pairs safe and change one archive at a time so you can bisect what broke.
• Other people's work: custom content in a private server's client belongs to someone. Learning from it is one thing, ripping assets for your own server is how you make enemies fast.

Frequently asked questions

Can I open an .epk file without the matching .eix?
Practically no. The .epk is a headerless blob of concatenated (often compressed and encrypted) file data. The offsets, names and type information live in the .eix, so without the index a tool has nothing to work with.

Metin2.Forum is a dedicated community for Metin2 developers, server owners, and players looking for reliable resources, discussions, and support related to private servers.

The platform provides a wide range of free Metin2 systems, development guides, tutorials, and useful tools to help improve and customize your server. You can also find carefully selected stable Metin2 serverfiles suitable for developers who want to create or upgrade their own projects.

Members can explore additional resources, including Metin2 server enhancements, server fixes and optimizations, along with customization content such as weapons, armor, and Metin2 costumes.

Whether you are building a new private server or maintaining an existing one, M2Forum provides a place to discover resources, exchange knowledge, and connect with other members of the Metin2 community.


EterNexus opens the pack but some files are missing or corrupted. Why?
Either the tool hit one of its known bugs (it skips some entries on certain packs) or the pack uses a newer storage type or custom XTEA keys the stock build does not know. Try a maintained fork or a modern archiver like m2a.py or PackMakerLite.

Will texture only mods get me banned on official servers?
They can. The rules do not distinguish cosmetic from functional changes, and integrity checks flag modified packs either way. Experiment on a private server that allows it or on a local client.

Which pack should I start with as a total beginner?
Something small and cosmetic like an icon or interface texture pack. Extract it, change one .dds or .tga file, repack, and confirm the client still starts. Once that round trip works you can move on to bigger edits.

That is the tour. If you have modded your client before, I would genuinely like to hear which tools you ended up trusting, especially on newer clients with changed keys. And if you are just starting and the extract or repack step fails, post the details below and we will figure it out together.