I have written in Squeak an interpreter for a programming language called SC5, based on the video game Space Channel 5.
Space Channel 5 is a fun game with retro Peter Max style visuals, and it
follows a space reporter named Ulala as she tries to beat aliens by
repeating their dance moves, "Simon Says" style. The dance commands are
"up", "down", "left", "right" and "chu" (each corresponding to a button
on your controller) but the sequel added the "hey" command also.
Because everything in the futuristic world of Space Channel 5 runs on
funky dance energy, computers must be able to accept dance commands.
Hence, the only commands available in the SC5 language are the dancing
commands from the game: "up", "down", "left", "right", "chu", and "hey".