While playing this game (since about 2007) I've been also attempting to mod it (like, all the time). Here is a collection of the most reliable features I've ever introduced to it.
The full version of the mod including the core and the XML. Install: unpack to the mods folder; Civilization IV vanilla version 1.74 is required (the...
The core DLL and the supporting python files. Will work with the vanilla game or mods that don't use an own DLL. Install: unpack to the Mods folder, select...