What does this program do?
H ; e ;
/ ; o ; W
@ > r ; l ;
l ; ; o ; Q \
; 0 P ; 2 <
d ; P 1 ;
. . . .
This is a “Hello world” program written in the Hexagony language, designed by Martin Ender. This is a two-dimensional programming language where execution proceeds along the 120° principal axes of the hexagon, directed by instructions coded as characters within it.
Esoteric programming languages are created as jokes, to illustrate how small and simple a programming language can be while remaining Turing complete, to mock aspects of widely-used languages, for just for fun. Here is an introduction to esoteric languages by Hillel Wayne, who has a companion paper, “A Brief Introduction to Esoteric Languages” with additional details and links to resources.
You can find information on 2,778 esoteric languages at the Esolang wiki. The esoteric.codes Web site has a wealth of resources and information about the fringes of computing.
But then, so are some programs! (Here is Wolfram rule 110, a cellular automaton whose program is eight bits long, which has been proven to be Turing-complete.)
You can simulate this, and many other cellular automata, with Fourmilab’s Cellular Automata Laboratory, which runs within your browser and doesn’t require you to install any software whatsoever.
But you ask, “what’s the most outrageous thing you did with a computer before the last twenty years?” And, there I went.
I wouldn’t be surprised that if the Wolfram Physics Project succeeds in finding the rule that underlies all of the physics of our universe that it can be represented in the most parsimonious fashion in fewer than 256 bits.
Hah! I know better than to get sucked into hours and hours of futzing. Esoteric+Programming+Languages is the trifecta.