[krapp]

If you're really into C, then you can't get much more "from scratch" than Handmade Hero (https://handmadehero.org/)

I stopped trying to follow it all after about 30 episodes and just pick and choose the parts I find interesting at the moment from the youtube archives (https://www.youtube.com/channel/UCaTznQhurW5AaiYPbhEA-KA).

[CmonDev]

Isn't he building a game rather than an engine?

[jason_slack]

He is building a game from scratch, but he isn't using an engine, so by nature he is building an engine too. I am sure there would be a lot of reusable pieces in the end he could re-use.

I am watching the series too. I paid the $15 to support the efforts.