>>719001682
>Player being part of Undertale only got popular because of Deltarune.
Popular maybe, but I definitely remember plenty of "the player is part of the game" speculation when Undertale was released. It got drowned out because limiting everything to in-universe characters made things easier for fan content purposes, which in turn is where the "Chara did all the evil stuff, Frisk did all the good stuff" got popular.
Undertale is one of those games where the fan consensus gestalt is divorced enough from authorial intent that trying to discuss the two is a clusterfuck, and that's bled over into Deltarune as well.