License

So this a long term project that i have in mind and will put to work in the future probably

So i want to create a game with the GZDoom Engine is it possible? and if want to put the game on steam will it be possible also?

You would need to use gzdoom-gpl since that version doesn't have any of the original doom code in it since that code isn't allowed to be used in commercial projects I don't think

GPL has always been commercially friendly, the only thing users are required to do is releasing all code (both remaining original and amended by user) under the same license and distributing it alongside with binaries. RHEL might be the best example of that.

6 hours ago, therektafire said:

You would need to use gzdoom-gpl since that version doesn't have any of the original doom code in it since that code isn't allowed to be used in commercial projects I don't think

This is a - pretty incorrect - chinese whispers version of the truth.

The doom sources *ARE* GPL. It's the other bits that were the problem in the past.

https://zdoom.org/wiki/license is pretty up to date on the issue

1. Talk to a lawyer.

2. The Doom source code is GPL which allows commercial exploitation so long as you release the source code (including to any source modifications you make). This is essentially a tacit permission from id that you can use the Doom source for commercial games and I doubt they care about "license purity"; I also doubt that anyone else is going to sue you for it either. At least one game based on ZDoom has already been commercially sold. However, I'm not a lawyer, this is not legal advice, and you should:

3. Talk to a lawyer.

Just pointing out that GZDoom-GPL is no longer required because GZDoom itself is now GPL.

Note that the code is one thing, but the game assets are another. For a commercial game based on GZDoom, you should make sure not to distribute any of the assets that are derived from the various games, like the fonts. (You will not need them anyway.) You may wish to read this thread.

Note that the dog sprites (for the MBF dog actor) have recently been replaced by free assets instead of the old Wolfenstein 3D rips, so that's one less worry on that front (even though you should not need to keep them anyway).

That's great news! I remember ripping them out of prboom for Debian, perhaps they can be turned on again 

5 hours ago, fraggle said:

1. Talk to a lawyer.

FYI, this is a mandatory step the moment you are selling any software or service. Mandatory like taxes and breathing to continue existing. You need to verify that you can sell everything you have, and that everything you have you own on paper.

You do not want to be caught out with a legal issue, because even if you don't end up with a court summons, you might find yourself stuck behind an insurmountable 90 degree climb to release anything else.