Hm, I've been wanting a mod like this for a good while now, and i was wondering if someone could possibly make something like this?.
what i mean is a mod that, when you click new game a yes or no option appears. "Would you like to configure the Enemy AI?" if you select yes you will be sent to a blank "flat world" with a machine with a bunch of buttons and a few tables with every unmodified gun in the game. these buttons when pressed will allow the player to fight a random assortment of enemies found in the game that regardless of what is spawned they will be allied to each other so they will fight you and only you. when spawned cover objects and structures will also spawn for you to use.
The first spawned enemies will have at first Easy mode AI to start with, and the more you fight and kill these enemies they will learn and start becoming more and more responsive you your attacks. keep killing them and they will eventually become quite hard to kill since they are learning from how you fight.
There can also be a sort of shooting range with at first slow moving targets, that will get progressively faster up to the fasted speed an enemy can be in the game, they should move around randomly so as to give you a challenge to shoot and destroy the targets that are moving in and out of cover. each target you destroy should earn you points giving you a reason to retry the test and further improve the enemies accuracy. This test will enhance the AI's or at least round the Enemies Accuracy to around human levels.
When satisfied with your results you can then save the AI profile. (so you don't have to keep doing this over and over each time you start a new game) and when you encounter Humanoid enemies (raiders, Gunners, Super mutants ect. from that moment forward they should behave relatively similar to how you would act in there situation. essentially you would be fighting yourself or a whole platoon of yourself in each encounter.
Sigh, yeah i know this is "not possible" er whatever. would be cool though. :/