This is going to sound absolutely crazy but I love the sound of keyboards and typewriters, it's a very good auditory stim for my ADHD.
To the extent that I even considered buying a mechanical keyboard to plug into my laptop.
This software is MUCH cheaper than that and now typing up stories and D&D campaign notes and essays and such is MUCH easier because my brain is constantly being rewarded with good stims!
I'm so extremely happy with this and would recommend it to anyone else with similar needs.