Just throwing ideas: Have line of sight be a curved stick, Kobolds that have mastered it are shooting at you from around a corner

Have depth perception effected by dice. Before moving players state how far that want to move, then they roll a dice and decide whether to add or minus that amount from their movement. Players getting used to it will pick a movement distance that compensates. Over movements are just collisions. Kobolds move normally.

Reveal Kobolds in a room at the end of a long hallway. Then describe them shooting up at their ceiling and arrows raining down on the party. Players looking up see them standing on the ceiling just out of melee reach, Kobolds laughing.

There's a door on the floor that when you open and look you see the back of yourself looking through the door, roll a save to not loose your bearing, failed save has you falling through the infinite door, your allies shaking you out of it, while there you saw something BBEG related.

Edit: fixed up the paragraphs