debugger documentation is actually all you need: https://docs.mamedev.org/debugger/general.html
There are a bunch of romhacking tutorials out there, I'm not doing anything special but I did work up to this level of complexity by starting at something very small.
In extremely broad strokes, you let mame or ghidra or whatever else disassemble the program rom binary, then you read through it and use the debugger to figure out what is doing what, and then make edits in the binary to implement the changes you want. I built some tooling to help make things faster, but it's nothing special.
Also, there's no legal issue with any of my work/code/patches/etc. I've just made an educated choice to pause this release, based on new information that was shared with me in private.
Respect on making the decision to pump the brakes for a minute, I know that couldn't have been easy. Your updates were filled with so much enthusiasm and joy behind the project. I think you single-handedly had us all completely engrossed with it. Looking forward to what churns out in the future man.
