Comment by csande17

Well, here Blender Studio is distributing the game's binaries for free while charging money to access the source code, and the GPL does prohibit doing that. And Dogwalk's Itch.io page claims that the code is GPL-licensed...

But if Blender Studio owns the copyright to all the GPL-licensed code in Dogwalk, they're free to distribute (or not distribute) it however they want. It does have the interesting consequence that people who don't have access to the open-source "production files" release probably can't redistribute the free-as-in-beer binaries without violating the GPL. Which is not the case for Blender Studio's films.