Ask HN: What’s the most creative ‘useless’ program you’ve ever written?

I recently came across the concept of “useless” programs – pieces of code that serve no practical purpose but are fun, creative, or challenging to write. These could be anything from elaborate ASCII art generators to programs that solve imaginary problems.
I’m curious to hear about the most interesting or creative “useless” programs the HN community has written. What was your motivation? What unexpected challenges did you face? Did you learn anything valuable from the experience?
Some examples to get the ball rolling:
1. A program that prints the lyrics of “99 Bottles of Beer” in binary.
A text-based game where you play as a semicolon trying to find its way to the end of a line of code.
A script that translates English text into Shakespearean insults.
Share your creations, no matter how quirky or impractical. Let’s celebrate the joy of coding for coding’s sake!