> Casey, meanwhile, has worked on a low-level game development video series for a decade and... never actually shipped a game?

He worked with Jonathan Blow on "The Witness"[0].

As the developer of the "Bink 2" video codec[1] and the animation tool "Granny 3d"[2], his code powers thousands of games.

[0] https://store.steampowered.com/app/210970/The_Witness/, [1] https://www.radgametools.com/bnkmain.htm, [2] https://www.radgametools.com/granny.html