so here's my dusttale take

and here's a bit of the story:

The human, reset after reset, has only massacred the monsterkind. But one day something changed. After waking up the skeleton remembered everything, every time he saw the surface, every fight he had, every death he saw. At first he didn't do much, but the next reset he still remembered, he remembered again and again, and at one point he broke. He went on the mission to overpower the human, but this didn't go as planned. A monster killing another monster is normally impossible in the game, and sans acheiving it completely broke the game, and so to try and fix itself, the game adapts to sans, changing things around him depending to him.

so yeah that's the story, i could tell more but it would be spoiling things and too long so i'm just gonna tell extra details.

-my idea is that through the game you feel like you're going through sans mind and each zone has a diferent meaning, one exemple i can give is that hotland is his anger.

-the clothing he has right now is from a room that appeared in asgore's home when sans was there, sans entered and knowing he's not sans anymore took the clothes.

-the extra strings appeared on him the more he though he was just a puppet of his own actions.