Module considerations

Documentation
1

This page is adapted from the old wiki page entitled Module Section Information. However, irrelevant information has been removed.

Overview

The Game Library is the central repository for players, designers, and publishers to store and access Vassal modules and auxiliary files.

Guidelines

See also * How to upload modules to the Game Library Service for more on the practical steps of uploading a module.

  • A project should be named according to the published title of the game.
  • It is advisable to post a link to the games BoardGameGeek page.

Files

The file size limit is currently ?MB. If you need to store something bigger, you should contact the site administrators.

Typically, files are of one of the following types

  • .vmod for Vassal modules.
  • .vmdx for Vassal module extensions.
  • .vsav for saves a game in a specific Vassal module.
  • .vlog for logs (recordings) of a session in a specific Vassal module.
  • .vdck for saves of card decks in a specific Vassal module.

Do not place Vassal files into ZIP archives. Vassal files are already compressed archives.

Other file types may be uploaded, such as PDFs and so on.

External hosting of modules and files

Users, developers, and publishers may prefer to host their work on their own website - for example to drive traffic to that web-site, exorcise content control, and so on - it is still, however, recommended to post files in the game library.

One reason is, that all faults during execution, whether caused by a module or by Vassal, may trigger posting an Automatic Bug Report (ABR) in the Vassal GitHub Repository. If the triggered bug is module-specific, then the specific module is generally needed to resolve the bug, and for that reason, it is beneficial to have the module stored in the Game Library.

Restrictions

The below is in no way to be taken as an exhaustive list of restrictions of use, development, etc. of modules based upon copyrighted work by third-party. Copyright owners may - within the possibilities of applicable copyright law and conventions - impose other restrictions. Project pages in the Game Libary are advised to explicitly state any copyrights and licenses.

Vassal modules containing copyrighted materials by GMT Games can be obtained and used under specific conditions listed in their FAQ (at the very bottom of the page). These amount to

  • At least one player must own a physical copy of the game.
  • Modules may not be used for commercial use in any shape or form.

Vassal cannot post modules of copyrighted materials, nor links to external web-sites with such materials, published or copyrighted by

This is in accordance with the wishes of those publishers.

Exceptions to the above are possible if an explicit permission has been granted by the copyright owner, and that is adequately documented in the project page.

(*)Avalance Press appears to be reevaluating their stance. However, until a clear statement is issued by Avalance Press, no module can be posted without explicit permission.

Documentation Index
3

I don’t know what the current limit is - perhaps @uckelman can elaborate.

It is hard to give a boiler plate as it depends very much on the module in question. First, check the considerations on How to upload a module. A good idea is to add a section - say Copyright and License to the project README.

Suppose you have a module that

  • Uses third-party graphics
  • Contains a copy of third-party rules

but otherwise is entirely developed by NN. Assuming you have obtained a license to use the third-party copyrightable materials from company Ajax Games, and you also have obtained a license to redistribute those materials, then a Copyright and License section could be

## Copyright and License 

All graphics and rules texts are © 2026 of Ajax Games.  These are used by permission of Ajax Games who has also granted permission to redistribute these materials with this module. 

All other materials are © 2026 of NN.

Permission to use, copy, and redistribute for personal use, free of charge, is granted by Ajax Games and NN.

If the third party materials are granted license to use only under certain conditions - e.g., like GMT Games which requres at least one player to have a physical copy, or if the materials can only be used for personal use (i.e., not in clubs, conventions, or similar), then that should be stipulated as part of the conditions. Take, for example Italy '43 released by GMT Games. A Copyright and License section could read

## Copyright and License 

Graphics (maps, counters, tables, etc.) as well as rules snippets are © 2025 of GMT Games. 

Other module developments © 2025 of Nigel Rabbetts.

GMT Games grants permission to non-commercial, personal use of their copyrighted materials provided _at least_ one player owns a physical copy of the game - see also their [FAQ](https://www.gmtgames.com/t-faq.aspx) (at the very bottom).

Note, if no permission has been given - implicitly or explicitly, for example as a license - then it is illegal (in those jurisdictions where the international convention is ratified) to distribute copyrighted materials.

Yours,
Christian

4

@slope game 2 The missing file size limit should probably be clarified, as it affects upload decisions. Also, is there a standard way to document copyright permissions on project pages to avoid confusion?

5

Please see answer above.