Mod Content Usage
Using Content From Other Mods
Unfortunately in some cases content is being lifted from one mod to another. It is a common misconception that just because a mod is free, its contents are also free for anyone to take and use.
Even if a mod is free, the creators of any original work included within it (sounds, models, story, maps) have the copyright to their work. This is true whether you are a high-school student, an adult or a corporation. Every author gains these rights by default when they create their work. They also have the law behind them if they decide to take issue with anything being used without permission.
The authors can decide who may use their work and how it can be used. If you see something in another mod that you want to use in your own mod, you should contact the mod creator and ask for permission.
Despite owning the copyright to your work, you might want to attach additional licensing information to your content. If you create content for mods and don't mind other people using your content (which benefits the community), it could save you the trouble of answering requests if you release your works under a Creative Commons license. See the Official Website to select a License for your works. Keep in mind that you can license elements of your work under different licenses.
Using Content From Other Games
Don't use content from other games without a proper permission.
The copyright information from the previous section is just as much in effect with commercial games. More importantly however, you are also under an End User License Agreement(EULA). EULAs usually forbid decompiling/modifying/re-distributing the game's content.
Keep in mind that most services (e.g. ModDB, Steam) will remove your work if it gets reported for containing infringing content (and actually contains it). Under the Digital Millennium Copyright Act (DMCA), once a web host finds/is notified of infringing material on their site, they are obliged to remove it or they must face liability for copyright infringement.
This of course also applies to using assets made by Frictional Games in mods for other games or your own games.
Frictional Games' Stance on Content Monetisation
Any content made on the HPL engines must be non-commercial. (source)
The following seem to be allowed. Keep in mind that they are not officially condoned, however.
- Accepting donations, for example one-time donations or ongoing donations on Patreon, or ad revenue from hosting your mod on a site. However, none of the content can be behind a paywall, for example for Patrons/donors only, or providing additional in-game content to Patrons.
- Paying someone to work on a mod. The key difference between selling your content and selling your services is that your creations are not being sold more than once.