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I am confused. I thought I would try and use a new game engine in order to expand my abilities, and found a nice engine called springrts. I was looking through the licensing info and it is licensed under the GPL 2 licence. If I remember correctly, does that mean that anything I make with it, I have to distribute the source code to?

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The GPL doesn't prevent you or anyone else from selling things, but it requires you to provide access to the source and all modifications to it, as well as requiring you to ensure that all source that touches it has a compatible license. – Lars Viklund Sep 21 '12 at 1:46
It is not obvious from looking at their site. They appear to have proprietary games listed on the example page. The only way to get an definitive answer is to ask them. If you get an answer from them you should answer your own question here. – Craig Sep 25 '12 at 19:43
@LarsViklund: Yes, but that's irrelevant here. The issue here is whether the game built on the engine is also covered by GPL. And the answer is very clearly no, it isn't. – Jan Hudec Dec 18 '12 at 9:43
@JanHudec: My comment is in a context that has since then been removed, either due to editing of the original question or removal of another comment I was referencing. Please refrain from jumping to conclusions. – Lars Viklund Dec 18 '12 at 11:36
It's common to confuse the GPL. You do not have to distribute code that you develop that uses the engine, but you have to distribute the source to the engine or provide a means to give it and / or the source code to any modifications to the engine. I think people get confused when they read the GPL and think that they have to distribute their source code. IF that was the case, many commercial people would not be in the business of using GPL code. – Brian Dec 18 '12 at 16:30

Under the proprietary section they say this:

These games may or may not be free to play. Modifying their content (i.e. the art assets) is not allowed without the game authors explicit permission, although the code is GPL and some games (P.U.R.E.) include large GPL-friendly content collections.

From Spring Engine - Games.

So it's not the code that makes them different, and they are following the GPL.

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in fact, they're not following the GPL if they declare that 3rd parties aren't free to modify the code. At the very core of the GPL is freedom of anyone to take code thus licensed and modify it, and indeed making those modifications (and anything that makes use of the original or its modifications) be licensed under GPL as well. – jwenting Oct 10 '12 at 13:05
@jwenting - I think they are making a distinction between the code of the games and the art assets - just because the code is GPL, does NOT mean that image, sound, and video files that are included in the game have to be available under the same license. – Michael Kohne Oct 10 '12 at 13:31
@jwenting: No, they are saying that the games built with it are not covered with GPL. Only the engine itself is. – Jan Hudec Dec 18 '12 at 9:39

No, in this case it does not.

In their list of games they are pretty clear that they consider the game data as using the engine rather than being derived work of it. So GPL does not apply to the game data.

Therefore you can put the game data under any license you want including fully commercial. You still have to provide download of the engine sources somewhere, including possible modifications you make to the engine code itself, but you don't have to do it for the game data source.

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