>>713039045
That's not the "whole gimmick" but it's part of it.
It's kind of acknowledging a huge blind spot with Undertale, where the whole idea there was exploring how your actions affect the characters and the game world but your own player character was practically a blank slate, to the point that you wouldn't even know they were supposed to be their own person until the end of the game.
In Detlarune, you know from the start that you've taken control of some kid and that they have their own life, personality and goals which might come into conflict with yours.