Affinity Easter Egg
Some common Easter Eggs found in Affinity software
The Style Menu changes to Cats!
In the late 1980s and the 1990s Macintosh Applications had all sorts of Easter Eggs. Most of them occurred when you performed certain actions. Every once in a while one would happen because of a date.
Some apps had Easter Eggs that would only be accessable via ResEdit. Check out my ResEdit blog post from a couple of years ago
My personal favorite was Dark Castle's Christmas Tree that would only appear on Christmas Eve and Christmas Day. I remember playing around with the system clock so that I could see it. I'll have to search my archive to see if I have some photo of it.
Thanks to RolandJuno on Flickr for sharing this classic Easter Egg: