Is That A Dragon or a Duck?

Adventure – based on the classic text game of the same name – was the first game ever to contain an easter egg. —Is That A Dragon or a Duck? (Metafilter)

It’s great to see Adventure get a mention, but no, the Atari version was a graphics game that really shared nothing besides the name with the Crowther/Woods text originial.

I see that Metafilter credited Memepool.