Not 100% but there must be some restriction because even the handful of OSS (not FOSS!) games do not bundle the source code on the release itself on, say, steam. the source code is linked on the license
>And yet Carmack gave it anyway.
carmack gave away the source code for old as fuck games, which is nice but also come on man, he used to work on oculus until last year, do you see him releasing source code for that work?
> They're either FOSS or they're not.
FOSS is not OSS, silly. If a codebase is released under the Apache or MIT license or those meme "buy me a beer" license, its OSS. If its released under any of the GPL licenses, then you're looking at FOSS. Come on man, this is easy stuff.