Now, before you get excited – this is nothing to do with chocolate!
Easter eggs in this case refer to hidden surprises and extras (just like an Easter egg hunt when you were a kid). They are aimed at people who like to explore (Free Spirits) as they reward people for just looking around and digging a little deeper than some others.
In games (and actually even in serious software like Office), Easter eggs have been around for a really long time.
An Easter Egg doesn’t have to be hard to get too, Disney’s Aladdin had a lovely nod to Mickey Mouse for the more eagle eyed amongst its players.