It is an emulator for a console that does not exist in real life. People make games for this "console" because they are fun to play and fun to program.
I sometimes think that passionate nerds love their niche so much they forget that other people might not have the foggiest of what they're talking about.
The same developer made PICO-8, which is better known: https://www.lexaloffle.com/pico-8.php