What happens if you kill everything in skyrim???? including all people and children?

If you use a mod to kill everyone, including the essential characters, then I imagine most of the quests would be impossible to complete. Random encounters, guards and animals will still respawn, and probably several of the locations in the game where there are unnamed bandits and necromancers and that sort of thing. Dragon lairs will also respawn. However none of the named characters will respawn. Assuming you haven't used a mod to interfere with that, too.

Depends on where you play. PC has mods to make it possible, if you're playing on a consual, then its impossible. Children can't be killed, or even hurt for that matter. Some NPC are essential for quest and the like, and even after their quest is complete, you still can't kill them. Guards and animals just respawn So you really can't,sorry.

Considering you cant kill the kids without a mod, and some of the people in the game cant be killed as well, and the animals in the wild such as the wolves, and anything else that can attack you, the just respawn when you get far away from the area, or travel from there to somewhere else, and then back. Basically, you cant even do that

You can not kill Children in the vanilla game and many NPC's are essential meaning you can't kill them. If you kill all the guards they have a similar respawn cycle to world enemies (bandits, wolves, draugr etc.) meaning they will be back in a few weeks.

You get taken to the Skyrim Nuremberg Tribunal and executed for war crimes.

Impossible with the game as published.

With Essential class NPC and respawning of bandit class and animals..

you unlock the mod chop shop, where you can loot enemies and take their head and trade them for one piece of equipment for each enemy, you can trade it for the M4 assault rifle, the tactical vest, combat helmet, 1911, stuff like that and more enemies spawn so you can use the stuff

You're going to have a hell of a time trying to complete quests, haha.