The last software I worked on in my previous company (a few months back), was a temporary replacement because they were switching techs. It was meant to be replaced within 2 years.

So, before I left, I added a kill. 2 years and 2 months into the future. First it spams the devs with emails "how is the tech upgrade going?" with no further clues. 6 months later it will start throwing random exceptions at random intervals. 6 months after that it just terminates the application immediately upon startup. Snuck it in between large commits, and since they stopped code reviews when I left, doubt they found it.

There is a setting in configuration with an obscure name to disable it all.

I marked the dates in my calendar. Would love to be a fly on the wall then.