What about GUI, sound, asset / resource management, levels / maps, quests etc.?
These are all good candidates for scripts. Most of the game can typically be written in a scripting language. Typically the only thing that may require being written in the core language (C, C++, C#, Java, etc) is anything that is performance critical or core game algorithms. It allows for faster development as changing scripts doesnt require a rebuild of the game. This answeranswer has a bunch more information on scripts vs core language
