That describes so many projects that I've seen, over the years.
One of my first programming projects, was maintaining a 100KLoC+ FORTRAN IV email program, circa 1975.
No comments, no subroutines, short, inscrutable, variables, stepped on by dozens of junior programmers, and the big breadwinner for the company.
Joy.
It was probably the single biggest motivation for my uptight coding style, since. I never want to do to others, what was done to me[0].
[0] https://littlegreenviper.com/miscellany/leaving-a-legacy/
That sounds challenging, and very early for email. Would I find it in the timeline or was it internal only?
https://archive.computerhistory.org/resources/access/text/20...
Proprietary store-and-forward system, run by a BT subsidiary, named Dialcom. Ran on Prime minicomputers.
I worked there in 1987.
[UPDATED TO ADD] And to add insult to injury, it was all on sub-VGA 300-Baud VT-100 terminals and line printers.
I spent a lot of time, staring at blue-striped paper.