Games are an awful vehicle for the exploration of psychology. Some of the best books and films are great because of their ability to get you inside the head of a particular character while they make a complex or interesting choice. Games, though, instead of trying to delve into a specific character's psychology, try to get you, the player, to experience the psychology yourself. There is never a time when this doesn't feel forced and contrived.
Imagine a scenario where you make a single-player game whose goal is to explore the regret of murder. In your game, you persuade the player to kill many people on his way towards his goal. You force him into situations where he is convinced he has to kill, both because you tell him he has to and because he is used to murder as a convention of the genre. At the end of the game, you let him realize that in the mechanics of the game, there was always hidden a way to not kill any of the opponents he encountered. You hope to induce the feeling of regret and sorrow on the player. But why should the player feel regret or sorrow? You, the designer, blinded him into believing one thing. The player has been tricked. He looks back and realizes that the whole experience was contrived, and anything you tried to get him to feel was just a result of tricky storytelling. There was no honestly in the entire interaction.
A book or film, on the other hand, can be dishonest, but doesn't have to be. Events can be contrived, but ultimately the question is "Did these contrived events seem realistic in the world? And have they had a realistic effect on the character as I understand him/her?" Questions like this are ridiculous when looking at a game. Any effect the events had on YOU, the player, were obviously unrealistic, as YOU know that they were contrived—a mere simulation. The degree of separation that a film or book has between the reader and the character is an essential part of honesty in art.game is undertale btw