Imp's More Complex needs (often called "IMCN" or "IMCNNV" for the New Vegas version) is a primary needs mod created by Imp for Fallout 3 and Fallout: New Vegas. is a mod created by Imp of the Perverse. This mod differentiates itself from other special needs mods or from New Vegas' "Hardcore mode" in its complexity.
Rather than the basic values of starvation, thirst, and sleep IMCN include values for calories, hydration, protein, nutrient, alcohol, and fullness. Additionally fat, carbohydrates, stimulants, and appeal were added in the New Vegas version. There is also a health regeneration system which ties into the player's protein and nutrient levels in lieu of food healing.
Beyond that both versions include timescale customization and the Fallout 3 version has full support for Fallout 3 Wanderers Edition (FWE) and all the Fallout 3 DLC, although the Fallout 3 DLC packages are no longer downloadable from the Fallout 3 Nexus.