Well, hold on - that's oversimplifying. Some developers do things like that, and some don't. Valve is an extreme example, but:
- They publish a free (as in beer) SDK and modding tools for Source, and allow people to submit mods to Steam - even if they use Valve IP, and charge users money for it (e.g. Aperture Tag). (However, users have to have purchased the original game to run mods, and removing this limitation or accessing the Source source code requires a commercial license.)
- They have the Steam Workshop, which allows users to, depending on the game, submit assets for potential inclusion in Valve games (with revenue share), and upload custom maps for others to use directly.
- They have released specialized tools such as Source Filmmaker and the Portal 2 map maker to assist with user-generated content.
- And, of course, many of their flagship games were originally community mods: Team Fortress, Counter-Strike, DotA.
...Thus it's hard to say Valve wants to "mistreat the customer" or doesn't want users to create their own content. Nor do they indulge that much in DRM. Yet thus far, they have not released any free software. Why?
I think it's mainly a culture thing. Free software games are essentially nonexistent. In PC gaming there are plenty of small developers, and lately there's a trend toward very early release and community engagement, all things associated with free software - but it's all in a context where developers can and want to make money selling games, and source access is not expected. This is nothing unusual, of course: in all of programming there are many, probably a majority, who are more likely to consider GPL a "cancer" preventing them from doing what they want than something to embrace. (In mobile this is basically everyone.) It's just that the pockets of free software enthusiasm which exist in other subfields aren't nearly as significant in gaming. In such a context, GPL releases would just be a distraction from supporting users/indies in the way they want, and so we don't see them.
I'm still holding out for a GPL release of Source 2, though... And, as a point of hope: while the new Unreal Engine is not free software, its licensing and development model seems very much inspired by it, and to be designed to provide some of its benefits while allowing Epic to make money.
- They publish a free (as in beer) SDK and modding tools for Source, and allow people to submit mods to Steam - even if they use Valve IP, and charge users money for it (e.g. Aperture Tag). (However, users have to have purchased the original game to run mods, and removing this limitation or accessing the Source source code requires a commercial license.)
- They have the Steam Workshop, which allows users to, depending on the game, submit assets for potential inclusion in Valve games (with revenue share), and upload custom maps for others to use directly.
- They have released specialized tools such as Source Filmmaker and the Portal 2 map maker to assist with user-generated content.
- And, of course, many of their flagship games were originally community mods: Team Fortress, Counter-Strike, DotA.
...Thus it's hard to say Valve wants to "mistreat the customer" or doesn't want users to create their own content. Nor do they indulge that much in DRM. Yet thus far, they have not released any free software. Why?
I think it's mainly a culture thing. Free software games are essentially nonexistent. In PC gaming there are plenty of small developers, and lately there's a trend toward very early release and community engagement, all things associated with free software - but it's all in a context where developers can and want to make money selling games, and source access is not expected. This is nothing unusual, of course: in all of programming there are many, probably a majority, who are more likely to consider GPL a "cancer" preventing them from doing what they want than something to embrace. (In mobile this is basically everyone.) It's just that the pockets of free software enthusiasm which exist in other subfields aren't nearly as significant in gaming. In such a context, GPL releases would just be a distraction from supporting users/indies in the way they want, and so we don't see them.
I'm still holding out for a GPL release of Source 2, though... And, as a point of hope: while the new Unreal Engine is not free software, its licensing and development model seems very much inspired by it, and to be designed to provide some of its benefits while allowing Epic to make money.