Mod settings file format

mod-settings.dat is a binary stream file format. The data is read from start of file until there is no more data. If there is no data and you are at a point where there should be data then the file is malformed. If you're at a point when you expect no more data but there is data then the file is malformed.

A C# example on how to parse the file format can be found here: https://forums.factorio.com/59851

The file format

The first 8 bytes are the version of the game the file was created in. After these 8 bytes there is one bool (1 byte), always set to false.

Next is a single Property tree

Sections

The loaded Property tree is expected to be of the Dictionary type with the following 3 sections:

Startup

This section is a Property tree with a key value of "startup" and a Dictionary value of mod settings.

Runtime Global

This section is a Property tree with a key value of "runtime-global" and a Dictionary value of mod settings.

Runtime Per User

This section is a Property tree with a key value of "runtime-per-user" and a Dictionary value of mod settings.