The original Kings Quest (on my PCjr, at least) had an interesting quirk that anything that was movable was drawn last. So you just had to spot that the rock a

The original Kings Quest (on my PCjr, at least) had an interesting quirk that anything that was movable was drawn last. So you just had to spot that the rock appeared a second after you entered the screen, or the mushroom suddenly showed up, that it was something you could interact with. The fun part was trying to figure out the magic phrase to affect an object, as not all of them were as obvious as "move rock" or "eat mushroom".