Speaking from my own experience with Undertale, I have to say I'm eternally grateful for not spoiling myself for once with the game before playing it (unlike virtually every other piece of media I come across, be it video game, anime, manga, book, play, tv show, etc). Especially considering what I've seen with other people being spoiled by raging fans, lol.
The one thing I saw that got me into the game was this gif.
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Anyways, sorry for derailing the thread (again), I just saw Undertale get mentioned and wanted to put my 2 cents into the discussion.