Relatively recently, I found and started watching the Handmade Hero series. In the series, Casey Muratori is basically coding a complex game from scratch (i.e. using no libraries beyond what is required by an operating system). You can read more by following the link above.
I’m far behind (and probably will never catch up) due to limited time, but it’s been a great series. While I have different opinions on some things Casey brings up (and certain items may only apply to different types of software), there is no doubt that he knows his stuff and is far more experienced than me. I’ve learned some neat tricks from watching, and he has encouraged me to think more critically about certain aspects of programming. If you’re interested in learning lowish-level programming in a language like C, I highly recommend checking it out.
Watching Handmade Hero also led me to find Jonathan Blow’s videos where he talks about a potential new programming language for games. His insight into flaws in current programming languages and proposals to fix some of these issues were fascinating, and Jonathan even has a prototype compiler for his new language that seems to work pretty darn well. I’m looking forward to seeing that new language progress.
Anyway, just wanted to say thanks to both of these guys. If those topics seem interesting to you, I recommend looking into their programming video series. Lots of neat learning opportunities.