Louis XXIV
Le Roi Soleil
They havn't put it in for a 'joke' its simply a marketing strategy. New XCOM content is coming out...
So some marketing woman no doubt says "I have a great idea, lets put introduce an XCOM unit into a game people are actually going to buy to serve as a constant advert which costs us nothing"
Not that people don't play XCOM anyways, I do, I'm sure a few others do, but this to me isn't just an Easter Egg, its shameless marketing...
I'd have to disagree. Firaxis has a very collegial studio. Both games are in-house and XCOM is made by a guy who has been with Firaxis for well over a decade. I think it's definitely a tribute. It's not an Easter egg in the sense that it's not hidden, but it's not great advertising anyway because it'll rarely be seen. Unless the Civilopedia says "available in stores," it's possible for many people to miss the reference entirely.