In Witcher 3 is it possible to kill the Nilfgaardian soldiers? I killed a level 17 soldier when I was still level 3 in the prologue part (White Orchard). Instead of dying and dropping loot he just stayed there like nothing happened. I also can't target/attack him since. Is it a glitch or..?
They aren't meant to be killed. In the tutorial area they are there to be designed to teach you not to steal from people while guards are around. If they kill you you just wake up after a while and lose some money, you don't even have to reload a save.
If you kill them they simply "respawn" and go about their day.