For me a modern and more adult kings quest would contain
1) Survival horror elements - which in a kings quest game means running away from monsters like in amnesia the dark descent and using your ingenuity + puzzle elements to elude them; like witch from kq1 or troll and donkey etc
2) Plenty of lighter elements to offset the dark parts; classic fairy tales but with the original grimm elements
3) Plenty of puzzles but in a modern seamless 3d world to explore; kings quest 1 was at the time the equivalent to skyrim today.
4) Game should not allow combat as in rpg but only puzzles to resolve problems
My two cents...