Source 2 will be free to developers, but it isn't stopping there. Valve bossman Gabe Newell has spoken of how he wants a more open world for developers.
Talking with MCV during this year's GDC, Newell spoke of how Valve is allowing other companies to use its tech for free—something that might not have come to pass if other companies had their way:
"We started to get pretty worried a while ago when we saw this sort of closing off. It was like Microsoft saw the iPhone and said: ‘We should make the PC more like that; people should have to go through us to have new ideas’. And we thought that sounded like a terrible idea. The iPhone should be more like the PC and the internet. Not the other way around. "We were happy doing what we were doing but we felt that, for our own sake, we needed to make sure that the PC and PC gaming continue to exist and thrive. Developers need the freedom to try out stuff; that’s how we’ve been successful."
Sure, it doesn't mean we're all getting free Steam machines and Vive headsets with our copies of Half-Life 3 that we're all given gratis, but that's because we're not all developers. If you are, Newell and Valve want to help:
"If there’s something useful, we’ll give it away. Somebody else will figure out another way to use it, as long as we treat it as a tool and not a straightjacket."