YMMV: Yume Nikki

  • Absurdly Sharp Blade: The Knife effect. It is especially true since Madotsuki is able to kill (almost) anything by stabbing it once.
  • Big Lipped Alligator Moment: Many, many bizarre things happen at random in the game and are never referenced again. But then, it's a dream, and there's no dialogue; it's only to be expected.
  • Broken Base: The spinoffs, with the manga particularly causing a firestorm within the fanbase.
    • Although, the hate has been dying down recently, due to Chapter 5.
  • Creepy Awesome: Uboa. Despite being terrifying, he's got a lot of fans and is one of the most memorable characters in the game. Madotsuki might qualify as this, too, since she's a Hikikomori with messed-up dreams and runs around killing innocent bystanders with a knife.
  • Crowning Music of Awesome: Has its own page
  • Death of the Author: Officially endorsed. The novels are authored by Kikiyama, but she has gone out of her way to state that they are only her interpretations of the game, and carry no more weight than any other.
  • Discredited Meme: Vomit-Chan - a reaction image of Madotsuki throwing up - is hated by fans (link NSFW), not only because it's propagated by those who are unfamiliar with either the character or the game, but also because such an event never even happens in the game.
  • Ear Worm: The Aztec Rave Box, among other things.
  • Ensemble Darkhorse: Quite a few. Uboa and Masada, especially.
  • Epileptic Trees: There are a lot, due to the fact that there is no plot or characterization at all. Many of these are Poison Oak Epileptic Trees.
  • Freud Was Right: At least the fans like to think so. Arguably, many examples in game are indicative of this trope.
  • Good Bad Bugs: The boosted speed trick, which makes exploration a lot easier.
  • Goddamned Bats: Some of the Toriningen. They don't kill you (really, nothing in the game can except gravity) but if they hit you, they'll send you to a secluded area that you can either escape by waking up or by using the Medamaude effect which takes you back to the hub.
  • Hilarious in Hindsight: Although Masada is often noted as Looking Like Cesare, he arguably looks even more like Tommy Wiseau. One poster of The Room even depicts Wiseau with slightly crossed eyes!
  • I Am Not Shazam: Thankfully averted; even those vaguely familiar with the game are smart enough not to call Madotsuki "Yume Nikki."
  • It Was His Sled: How to make Uboa appear, as well as his very existence, which ruins a fair amount of the shock of discovering him. Then again, he has a 1 in 64 chance of appearing, meaning that most will never see Uboa anyway unless they either get very lucky or they explicitly try to find him. It can still be very shocking, however, when trying to find him, failing multiple times, doing it more just for the heck of it, and he suddenly appears.
  • Late-Arrival Spoiler: If you haven't played it yet and are planning to, better do it before the video playthroughs, Fan-Art, and even official merchandise spoil it for you.
  • Memetic Sex God: Masada and Uboa.
  • Memetic Mutation:
    • Many of the named NPCs — specifically, Monoko and Poniko/Uboa(aaaaaAAAAAああああ) — have become just as popular as Madotsuki herself on certain Image Boards.
    • ah not tan neet are not tan neet centimeter has become this for video sites.
    • Within the fandom, "NASU IS VERY EXCITING!" and "Let's monochrome ourselves!"
    • Little do you know that Uboa actually has a smooth, English voice and enjoys long walks on the beach, that is after he sends you to an alternate dimension.
    • One that we can take credit for is pointing out that Uboa looks an awful lot like Che Guevara.
    • A drawing of Madotsuki vomiting has circulated around the web and received many spin-offs.
    • In Youtube Poop and similar videos it is somewhat popular to play the infamous credits music when a character falls from a height.
    • A fair amount of Puella Magi Madoka Magica fans "adopted" Madotsuki and make fanart of her as a Puella Magi, due to an eerily plausible WMG which says that she was.
  • Nightmare Fuel: So much of it.
  • Self-Fanservice: Many of the characters are portrayed in fan art as cuter and/or sexier than what their sprites would normally suggest. Masada gets the most of this, but special mention goes to Shitai-san, who's supposed to be a dead body.
  • Ship-to-Ship Combat: If you don't ship Masada/Madotsuki, be prepared for a virtual shove-in-a-puddle. And the people who don't ship them are usually too busy shipping him with Shitai.
    • It's difficult to find femslash shippers in Yume Nikki, but there's a few people who enjoy Madotsuki/Poniko, or Monoe/Madotsuki.
    • The Dream VS Dream April Fool's is a mock dating-sim so everyone's ship needs get catered, hilariously so.
    • Fan-Preferred Couple: In addition, the Masada/Madotsuki ship tends to be pretty popular with fans despite the fact that the game has no dialogue.
  • Sweet Dreams Fuel: Certain places, like the sky garden are strangely relaxing.
  • Tear Jerker: If you want to read some of the fan theories, getting tissues beforehand is highly recommended.
  • That One Level:
    • The very big Hell maze.
    • The teleporter maze as well. While it lacks in size, it makes up for with a confusing network of Teleporters and Transporters.
  • True Art Is Angsty: The reaction to the unofficial Alternate Ending here. The general response is that it not only undermines the themes of the game, but also the ambiguity of its reality. That said, it does have its fans.
  • True Art Is Incomprehensible: A lack of dialogue or plot forces you to come up with your own meaning.
  • Ugly Cute:
    • Monoko is what you get when you combine Body Horror with Moe.
    • Uboa, of all things, tends to get this treatment in fanart. It does have a big wide smile and eyes that suggests it's quite happy.
  • Westerners Love Madotsuki: According to post No. 1420 on this page, Kikiyama was surprised to know that Yume Nikki was a lot more popular in the West than she expected.
  • The Woobie:
    • A very popular representation of Madotsuki.
    • Seccom Masada-sensei is often considered one as well, given where he resides: a spaceship in the middle of space, with no sentient company. If you take out your knife, he tries to get away from you. And then there is the table with two chairs, as if he would hope someone would come to him...
    • Mars-san, who's trapped alone in a cavern under Mars, looks as if it's crying, and its background music certainly doesn't help. It should be noted that it appears later on the same path as Secom Masada-sensei.