It's just a joke.

Also Caesar in Gaul resembles something more like the Penninsular Dlc for Napoleon. It's a small map covering one area (Spain in that case, France in this one) has added some new stuff and that's about it.

So far there are three more dlc planned. Free or not I have no clue.

Source: http://steamdb.info/app/214950/#section_dlc

Edit: Ninja'd