You should give it another chance. The Windows aspects are very minimized. Make a display buffer, make an audio buffer, read a file, read the keyboard. Setting these up only take a few episodes. The other 100+ episodes deal with raw buffers.

From the frontpage:

    Will the game support multiple platforms?

    Yes! Windows will be the first platform, since it is currently the most
    common gaming platform, but the series will later cover (at least) Mac,
    Linux, and Raspberry Pi. Portability will be a major topic in the series,
    so all the code will be structured to demonstrate how to write code that
    is easy to port to new platforms.

I hate to tell you this but a large majority of game development is done on Windows.

Sadly agreeing here. I'm a Mac person and the only thing I still use Windows for is game development. I do my game development on a mix of Windows and Mac, but the reality is just that some of the tools I need/use are Windows only.

The situation is much better than it was 5 years ago and it is certainly possible for people to develop games without using Windows.

People were porting it to Linux with SDL at Handmade Pengiun: https://davidgow.net/handmadepenguin/

I am not sure if they've kept up or not, as I haven't kept up with the series, despite my attempts. Nothing against the series, I just haven't taken the time to follow yet.

Not sure if it's the same one, but there is a SDL-based port that is up-to-date. There's also native mac ports in various levels of completeness.

Casey recently added a github repo (with auth) and so it's a lot easier to keep up with the changes.

And C in a C++ mix. Not exactly vanilla C.