We know people hate legalese, but this is important. This applies to everything which is submitted.

You must be careful when basing on existing graphics or sounds. Most Doom projects are lax on reusing intellectual property—​there are many mods which contain modified Doom sprites, for example. However, due to the nature of this project, we do not have the same liberty to rip as we please.

The general rules go as follows:

• You must have permission for everything you submit. If you make your own resources, do not base on resources from Doom or any other restricted work. If you take work from other places, please make sure that the work is freely-licensed or that you obtain permission to include it in the Freedoom project. They may not place additional restrictions compared to the normal Freedoom license.

• Do not try to emulate Doom resources exactly. Where possible, put effort to make new versions look visibly different from Doom. This is a tough call, because our compatibility with Doom mods limits how far we can deviate, but it is feasible.

• Be especially careful of “free textures” (or “free sounds” or “free graphics”) sites. Although these would appear at first to be okay to use, many are free for “non-commercial use only.” One of the things we want to be able to do is put this in GNU/Linux distributions (which can be sold or developed commercially).

All levels for Freedoom must be vanilla-compatible, requiring an expanded-limits or limit-removing engine is not permissible. This means you may not exceed the limits of the original Doom engine, and do not depend on additional mapping features. Levels should be in Doom’s original format, not in “Hexen”-format.

It is sensible to also heed the following guidelines:

• Make sure that skill levels are implemented, and that all multiplayer start points, both cooperative and deathmatch, are present.

• Try to make levels appropriately difficult for their position within the progression of the game. Also bear in mind that not all players may be as skilled a player as you.

• Do not use tricks that exploit Doom’s software renderer; some engines, especially those that use hardware accelerated rendering, may not render it properly. Examples of tricks to avoid include those used to simulate 3D bridges and “deep water” effects.

• Test your levels in Chocolate Doom to make sure that vanilla compatibility is maintained. This is an engine with strict adherence to vanilla Doom limits and bugs, and working in it assures that levels can be played with any Doom engine.

• Use a Doom editor to check for errors. In Eureka it’s possible to check for errors with the Check / All menu, or by pressing F9.

• If possible run make test and fix any errors found. Note that some of the errors can be fixed by make fix.

Graphics should generally have the same color and size as the original Doom graphics, as to remain compatible with mods. Otherwise, levels may end up looking like a nightmare in design. They may be thematically different as long as it doesn’t clash.

Doom uses a fictional corporation abbreviated as “UAC:” this is trademarked by id Software and cannot be used in Freedoom. Instead, use the initials “AGM” for Freedoom.

Freedoom always needs help with documentation, so please send your patches, but keep in mind:

• We use AsciiDoc for writing the documentation. AsciiDoc is a simple plaintext-based format which is simple to read and write in its source form, and can generate nice HTML documents out of them.

• Headers are formated in a wiki-style format, this makes it easier for Vim (perhaps other editors, too) to automatically re-format text.

• Text is kept at 72 characters wide. In Vim, you can set the editor to automatically insert line breaks as you’re typing by performing set textwidth=72. Special exceptions to the width rule might be allowed when necessary (for example, inserting long URLs).

The most common, and a fairly simple method, to submit your work is by posting it on the Freedoom forum on Doomworld Forums. This allows a great number of people to review the contribution and provide feedback, although the registration process is known to be cumbersome.

An alternative to using the forum, is to post your submission on the issue tracker, which may also be peer-reviewed and provide a feedback cycle.

Unfortunately, the Freedoom project cannot provide hosting space in the form of a web page nor FTP, however there are many free file hosts to use when you need a location to upload files. Sites and services such as Dropbox and Mega, as well as others, are common and should be simple to use.