"Playable Quotes for Game Boy Games" by Joël Franušić and Adam Smith

They built awesome stuff to "quote" software including it's actual state, and allow the quote to be replayed without the need of having the software which was quoted! The quotes can also be used to steer the software at that point in time, e.g. play a game, move the mouse in a spreadsheet, etc.

The quote is limited to the area of memory which got changed while the quote was recorded. Any outside access will restart the quote.

I can't wrap my head around, how this could be used in real-world settings, but this feels important.