How is it not possible? :/ I currently use modding for my projects, or am I missing something? I currently have certain functions that will load text files that pertain to building objects or effecting the game out right, including scripting, custom game characters, items/weapons, levels, etc... I created these systems so I could easily add new levels, characters, items and levels without having to recompile the game.
I'm probably missing something.
I figured you had to make your game moddable, didn't know there are other ways.