For more details and additional information, check Modding Support on the Egosoft wiki.
This section contains information and guides for modding X4: Foundations.
What an X4 extension is made of, from an empty folder to a package the game loads - content.xml, the folder map, how a file joins the game, text files, and packing into catalogs.
The Mission Director and the AI script engine, and the command vocabulary both of them share.
X4's interface is Lua, and it is moddable without touching the executable.
The tool that packs and unpacks X4's cat/dat archives - every switch of the command line version, and the GUI screen by screen.
One extension package that carries different content for different game versions, using version-named catalogs - the naming rule, the four loading rules, the diff catalogs added in 9.00, and how to build one.
What changed for a mod author between the last two game versions - every name the game dropped, added or reshaped, each one linked to its own row in the reference that carries it.
The game's command line - where the options go on each store, the two switches that produce a debug log, the filters that decide what goes into it, the complete list of what the parser accepts, and a section a mod author can send players to for a bug report.