It’s impressive when a “demake” puts Super Smash Bros. on a calculator or makes modern PlayStation games look like first-gen, but Pekka Väänänen may have just topped them all by getting the seminal first-person shooter Quake to run on an oscilloscope:
An oscilloscope is a measuring device that visualizes changing voltages (or inputs like sound waves that can be interpreted as electrical signals) over time in two dimensions. What Väänänen has done is written code and used programs to generate lines from simulated electrical inputs via a computer running Quake. The rest of it is far too technical for me, but Väänänen gives a complete description of how Quake makes it onto the machine here.
You can watch the whole test below. It looks surprisingly playable after your eyes adjust to The Matrix code-style visuals: