All data relevant for the game (e.g. how much costs building the castle?
What cultures exist? Can my priest overclock his "Wololo?")
are stored in a binary format in the file empires2_x1_p1.dat.
The format is described in the huge struct definition.
These data files are basically a huge tree structure. We don't handle cross-references to make this tree a graph in the convert script (like id mappings, e.g. villager has creation sound id 42, sound 42 plays the 1337.wav).
All data values are exported (in Python) to human-readable formats, and get imported by the C++ Engine again. The storage format is completely replaceable that way.
For simplicity the minimal format is CSV.
The data will get converted to nyan, our custom data language.
It's designed to be redundancy-free, well readable and specially optimized for
moddability.