ScummVM is a free (and open source) software. Does that mean I can do anything I want with it?
Not quite. Using a free software comes with certain rights, but also certain obligations. At its core Free Software rely on a set of four freedoms:
- Freedom 0: The freedom to run the program for any purpose.
- Freedom 1: The freedom to study how the program works, and change it to make it do what you wish.
- Freedom 2: The freedom to redistribute copies so you can help your neighbor.
- Freedom 3: The freedom to improve the program, and release your improvements (and modified versions in general) to the public, so that the whole community benefits.
Based on these, there are many different free software licenses that each have their own set of rights and obligations. ScummVM is using the GNU General Public License version 2.
You can read more on the Wikipedia page: https://en.wikipedia.org/wiki/Free_software
Can I sell a game using ScummVM?
Yes, you can, but there are requirements you need to fulfill (see the next question). One important aspect is that while the executable is governed by the GPL license, this does not cover the game data. So you are not obliged also to provide the source for the game data for free.
So what are the obligations if I want to use ScummVM to release my commercial game?
You need to comply with the GPL v2 license used by ScummVM. In a nutshell, this means that:
- You need to provide with your software a notice that the game executable (or part of it) is subject to the GPLv2 license together with the full text of the license.
- You need to provide the ScummVM copyright file with the game.)
- You need to provide the full and exact ScummVM source code you used, whether you modified it or not. It can, for example, be provided with the software, or you could have a link on your website or store page to download it separately. If it is not provided with the game, you need to ensure that users can easily find the source code at the time they download the game.
If I sell a game that uses ScummVM, am I required to contact the ScummVM project beforehand so that they are aware of it?
No, but we would definitely welcome such approach. See http://www.scummvm.org/contact/ for information on how to contact us.
If I use ScummVM for my commercial game, do I need to credit the ScummVM project?
No, you don’t need to do it, but you have to retain all ScummVM copyright notices. However, we would, of course, appreciate if you do it. This could include:
- Indicating on the store page for your game that it uses ScummVM, which is licensed under the GPL v2. This might be a good place also to provide a link or indication on how to get the source code you are using (see the obligations in the previous question).
- Indicating in the documentation for your game that you are using ScummVM.
- Keeping the splash screen that briefly shows the ScummVM logo when starting the engine.
If I modify the source code for my private use, do I need to make the source code available to others?
No. You only need to make the source code available if you distribute your modified executable. We, however, encourage you to make the source code available (for example by using a free account on github) as it may be of interest to others.