So I had this idea for a visual novel mechanic, probably inspired by playing too many Infinity series games, where the player takes the role of a “ghost” who can’t actually talk to any of the characters, but can interact with their environment when no one’s looking. At the beginning and end of every scene, you would get a chance to either remove objects from the “stage,” or place things that you’ve taken in previous scenes. One scene might be set in a kitchen, for instance, where you’d get the opportunity to take a knife from the counter and later conveniently leave it at the scene of a particularly tense fight.
I have a feeling this has been done before, but I can’t recall where.
Edit: I suppose I should mention that the idea was to have the stage-setting replace choices as the primary plot branching mechanism. Going back to the knife example, let’s say the climactic dust-up is between Alice, who is relatively weak physically, and Mallory, who’s fairly strong. Leaving the knife for Alice in that scene would thus mean the difference between her getting overpowered almost immediately and her having a shot at fending for herself. (In fact, my biggest qualm with this concept is that it could quickly turn into a combinatorial tar pit given enough manipulable objects and scenes.) A few people have showed me adventure games with a “ghost director” mechanic at their core, but they all seemed fairly linear plot-wise.