Please see developer blog for information on modding. Modable text data files are in JSON format.
Only one mod can be loaded at any time. Players are encouraged to combine all the mods they wish to use into a single mod, if they want to use more than one 
Mod File Information
On Windows platform, new mods can be saved to the \users\%username%\Documents\My Games\Big Pharma\Mods folder. Each mod needs its own subfolder here. You must include a modinfo.data metadata file or the game will ignore that mod. Additionally you can add any files from Big Pharma_Data\GameData that you wish to modify. The game will read data files from your mod instead of the default files, with the exception of strings-en.data, which will ADD to the default strings-en.data file data. Modders are encouraged to note if they overwrite effects.data in their mod so users will be aware they can only load one mod that does so.
- modinfo.data -- Required file. If this file is not present in your mod folder, the game will ignore it.
- effects.data -- if included, the mod's copy will overwrite the base copy when loaded (instead of appending)
Modders are encouraged to provide all localizations for any of the files below they choose to include:
Marketing and Malpractice DLC
To make your mod compatible with the Marketing and Malpractice DLC, you need to include a set of files in a subfolder called "MM". When enabled, the game will automatically use these files in preference to the ones included in the DLC.
To make sure your mod supports the new machines included in the DLC, it is recommended that you use the copy inside the game's own MM folder as a starting point. E.g. Big Pharma_data/GameData/MM/research.data.