Licensing the Doom Engine for commercial use

I am heavily considering using the Doom Engine for a commercial FPS I am in the initial planning stages for. Does anyone know the cost to use the engine or legal status of it (freeware etc.)?

IIRC the Doom Engine is GPL-licenced, which (IIRC) means that you may not use it for commercial purposes. But I don't know anything about licences, so someone who's more into that matter should help you.

https://github.com/marrub--/GLOOME/ seems to be the only way todo it atm.

Probably better to use GZDoomGPL as GLOOME isn't being actively maintained anymore.

bzzrak said:

IIRC the Doom Engine is GPL-licenced, which (IIRC) means that you may not use it for commercial purposes. But I don't know anything about licences, so someone who's more into that matter should help you.

Wrong. But you still have to provide the source code for the executable.

Thanks to the doom.wad precedent, you can make your own commercial data. What you can't easily do (because if you try, others will easily remove it) is digital rights management, due to the nature of open source software.

bzzrak said:

IIRC the Doom Engine is GPL-licenced, which (IIRC) means that you may not use it for commercial purposes.

printz already answered, but I'd add: not only does the GPL not prevent you from using the code for commercial purposes, it explicitly guarantees that you may use it for commercial purposes. I'd direct you to the GPL FAQ's entry on this: Does the GPL allow me to sell copies of the program for money? and Does the GPL allow me to charge a fee for downloading the program from my distribution site?.

Answering the original question: your options here are basically:

• You could contact Bethesda (id) and inquire about obtaining a commercial license to use the engine
  
• You can use the existing code under the GNU GPL, which already allows you to use the engine commercially, with the catch that you must also release the source code to any modifications you make to it.
  

I'd argue that the GPL route is the easier route to go down unless you're really worried about sharing source code. Bear in mind that the commercial licensing route only applies to id's code and not any of the work source port authors have done.

None of this licensing applies to any ACS scripts or add-on WADs you're planning to write; if you're not planning on making any source code changes to the Doom engine at all then the GPL route is clearly and unambiguously the route to go down.

fraggle said:

You can use the existing code under the GNU GPL, which already allows you to use the engine commercially, with the catch that you must also release the source code to any modifications you make to it.

Not necessarily a big catch. Basically, you sell your game and not the engine it uses. A GPL'ed engine doesn't imply your resources are free.
Actually Doom is the best example: A commercial game running on a free engine.

Exactly my point. In other situations people often have hangups about the GPL because of its copyleft feature, but this is one scenario where it really shouldn't matter at all.