Interesting reading.
My longest ever 6502 program was just over 5,000 lines. It was a game written originally in ODS (Ocean Development System) a cross assembler that used a C128 in 80 column mode to target a C64 using the user port to transfer the code. I had some friends in the industry way back when I got this from, and after using Turbo Assembler on the C64 this made things a lot easier/faster. I think this was maybe a precursor to PDS but im not 100% sure.
I recently wrote a small python script to convert the tokenised source code from ODS to plain text. If anyone is interested pm and ill send it to you.
There was a cartridge in the back of the C64 that held the program that managed the file transfer from ODS on the C128. This is lost now, and if I can ever be bothered I might write some code to try and get it working again.
I found my original source code and I had converted it across to Laser Genius assembler so I could link the multiple source files to generate the final program.
Comments are a thing I thought were unnecessary
Looking at some of my old source code I havent a clue what is going on, wish I had commented it. Let me know if you want to see what 5000+ lines of uncommented code looks like