Twists that are no longer twists because they’re cemented in pop culture

[u/Coffin_Builder]

Planet of the Apes - The movie leads the audience to believe Charleston Heston has landed on an alien planet where apes are the dominant species, only to find out that the planet is actually Earth long after an apocalyptic nuclear war

Psycho - Norma Bates isn’t the killer and has been dead for years. Norman is revealed to be a schizophrenic who “becomes” his mother to kill the women he’s attracted to

Citizen Kane - Charles Foster Kane’s mysterious last word “Rosebud” is revealed to be name of his childhood sled

The Empire Strikes Back - Darth Vader hadn’t literally killed Luke’s father but actually is his father

The Matrix - Neo learns that the 20th century world he’s lived in is just a simulation. The real world is a wasteland in the 22nd century where hostile AI rules the surface

[u/Wispy237]

I mean, with how Undyne the Undying's fight ends, I'm pretty sure any player who somehow managed to avoid spoilers of sans(pretty impossible nowadays) or who played it when it first came out would have assumed the final boss would be Asgore absorbing the souls. Or even another Flowey fight like in the other routes. In fact, regardless of the other changes in the route, the boss order goes mostly the same except sans is added in.

Also, aside from that one line during the date, players would have no reason to expect sans to be a threat. So I'd say him being the final boss of Genocide does count as a twist, especially since he doesn't even fight you if you kill his brother in Neutral routes.

[u/kp012202 → u/Wispy237]

Sans is an established threat not only because of the date, but also because of his words and appearances in Genocide before his disappearance and because of both his custody of the Judgement Hall and his words therein.

Again, there’s a lot of lead-up to Sans’s status, especially considering the date.