Specifically, how difficult would it be for an indie developer to implement a system similar to the MBTI so that the player character's dialogue, actions, and choices will change, according to the assigned MBTI type?
This may be limited to the snarkiness of the player character's responses, the character being more reluctant to go to a social event, how well the character will respond to criticism, etc.
It would help to reference games that have done this or something similar.
EDIT: For those that don't know, the Meyers Briggs Type Indicator is a way of measuring someone's personality based on 5 variables, (the last of which is usually ignored) in order to get 16 (or 32, including the last variable) different archetypes.
Extraversion vs. Introversion determines if you 'regain energy' by interacting with others, being the centre of attention, etc. or by being alone, doing such activities as walking, reading, and introspection.
Sensing vs. iNtuition determines if you prefer to absorb new information by focusing on facts, statistics, and details, preferring ideas with practical applications, or imagining the possibilities, exploring concepts for their own sake, and looking at deeper meaning.
Thinking vs. Feeling determines if you make decisions using logic, value justice, enjoy finding flaws and playing devil's advocate, or base decisions on personal values, and are more about how things should be.
Judging vs. Perceiving determines if you use T/F attributes to interact with the world around you, or S/I attributes.
Perception tends to make people want to keep their options open, and make external dealing decisions on the spot, rather than in advance, while Judging tends to be linked to making a plan and sticking with it.
Then, there's Assertive vs. Turbulent, which determines confidence in decisions. Assertive individuals supposedly are less affected by stress, which has the side effect of it not affecting their performance that much, whereas Turbulence is related to perfectionism, completionism, and panicking.
People cannot be fitted neatly into 32 different categories, as many people are near the centre for some of the variables, and it is therefore better to consider these archetypes than actual categories that everyone falls into. If as well as left and right there was also a 'middle ground' classification, instead of 32 personalities, there would be 243.
The personality system in question would not have to be the Meyers Briggs, and indeed it probably should deviate from it in a few areas for copyright reasons. The purpose of giving the PC an in-game personality is so that the player can relate to them, not so they can emulate the player, so the Forer effect actually works in the Game Designer's favour.
How feasible is it, therefore, to integrate a system such as this into a game such as an RPG?