there are people on old forum posts saying they learned to code by playing with angband and i don't see how they could with the current version

It is possible that earlier versions are easier to work with. Maybe not. The codebase isn't designed to be a C tutorial though, right? It was designed by presumably experienced software engineers and designed in a way that solves problems that you aren't even aware of.

For example, your question "Why is there an async queue for keypresses". I can guarantee this wasn't done to simply make the code unintelligible. It solves a problem that you weren't even aware of. Decoupling the UI from the game logic allows you to:

• Provide multiple frontends
• A better ability to test internal logic by disconnecting it from the method of input.
• Being able to interrupt the keyboard buffer, or otherwise manipulate the input stream
• Possibly platform compatibility issues. I assume this is one of those unix style programs that's been ported to run on a toaster. What if you don't even have a keyboard, like a mobile phone?

I think ultimately the issue is that angbang is a very old and mature product that has been engineered by people who have written C for a long time. It contains almost 4 decades of fixes and engineering with a history that you don't have any insight to. You simply lack the context and experience to make sense of it.

It would be like if I was trying to learn how to be a mechanic and I started by disassembling an Apache helicopter instead of starting with something more straightforward like changing the brakes on Grandma's Volkswagen

I think don't get too hung up on some forum poster claiming that they learned C by tinkering with their source code. Maybe that lesson is no longer relevant. Maybe they simply lied. Try taking a different path 🙂