His bid for recognition eventually paid off spectacularly — in Steven Spielberg’s 2018 movie “Ready Player One.” To save his world at the movie’s climax, Parzival, the hero, must play Atari “Adventure” and unlock its Easter egg. “You see, Warren Robinett was proud of Adventure,” Parzival explains as he plays. “That’s why he created the first digital Easter egg!”

These days, Easter eggs are anything but acts of defiance. They are meant to entertain, to lure potential hires, to pay tribute to executives — or to amuse the programmers themselves.

Google’s Mario maps

At Google, there is a long tradition of Easter eggs, which have the full support of the company.

“It helps establish software as an art form, following in the footsteps of painters and musicians and craftspeople sneaking little jokes and references into their work for literally centuries,” said Dan Sandler, who works on the Android smartphone software.

Mr. Sandler has built an eggy surprise into every version of Android since 2011. For the current version — Android P — he created a secret painting app.

“One of the themes in the P release was ‘digital well being,’ the idea that you should be able to choose a balance of screen time and non-screen time,” he said. “In my paint app, over time, the strokes you draw fade away to nothing, like a Zen drawing board.” (He notes that you can tap the hourglass to pause the timer, “if you must.”)

There’s no Save command, either. “This is another Zen thing: Don’t cling to your creations,” he said.

In the Google Maps division, the best-known Easter egg appeared on March 10, 2018. It was International Mario Day (Mar10, get it?), celebrating the goofy Italian plumber from Nintendo’s video games.