Hello togheter
So to explain a bit more me question: I know that if you use GPL Software or components your software also needs to be published under GPL. And this states that the price must just be so high to cover your expenses (so no real win). How did Valve handle this? Because their engine is a modified quake engine.
The GPL states that you can only charge a nominal fee to cover expenses when making the source available, as required. You can charge anything you like for the software you built from that source code. Many multi-billion dollar businesses keep their thousands of employees well paid by selling GPL software and still manage to pay juicy dividends (eg. IBM/Red Hat, Google, Microsoft). You are making the mistaken assumption that Free software must be free as in beer, not free as in speech.
Was the Quake engine always GPL, or was it released as GPL only in later versions? Did valve license the Quake engine from the copyright holders, which means they could have licensed it under alternate terms? Is their engine actually a modified Quake engine, or is that just a rumour from the internet?
ID could give Valve a commercial licence and later open source their programs under GPL. There is nothing forbidding a copyight owner to give out different licenses. (IIRC, I read ages ago that is what happened.)
I can't recall the timelines of the GPL release, but if it was before or after Valve started work, almost certainly paid ID tech to get the source code under a different licence (I think Valve confirmed at some point at least some of the engine code was still Quake, although they replaced a lot of it entirely).
The company/people that own the code are free to release it under as many licences as they like. This gets complicated with many contributors, as if one owner disagreed, all their contributions would have to be somehow removed, very hard for long lived code projects. Generally an employer will include in a contract that they get ownership for anything made by employees. They will likely also require that they have full ownership for any outside contributions before merging them.
For another example I believe MySQL does this (Enterprise Edition). A quick search for their contributing requirements says you must sign an “Oracle Contributor Agreement”, which will give Oracle ownership of the code to do as they please (for example merging into the GPL release, and their Enterprise Edition), they won't accept a patch under the GPL. MariaDB is I believe completely stuck with GPL, they would need permission from Oracle, and anyone that owns contributions since then to dual/re licence.
Valve paid to ID software 500.000$ for a license of the quake engine. Then they modified heavily and it evolved into Gold Source engine.
