* AdaptationDisplacement: A minor case: when the 2019 anime began airing many watchers were unaware that it was originally a revolutionary computer game from 1996. Cue many immediately accusing it of [[TheMockBuster ripping off]] ''VisualNovel/SteinsGate'', despite the latter more likely being the one taking influence from ''YU-NO''. [[OnceOriginalNowCommon Many didn't understand why the anime had so many cliché tropes, despite the game popularising or originating many of them.]] The word about its origins spread quickly, however.
* BrokenBase: The remake's artstyle. Some consider the new, more vanilla artstyle to lack soul and identity compared to the original, while other argue that the original game also had a very generic artstyle at the time, and that the remake tones down some of the most ridiculous, {{Stripperific}} outfits.
* CompleteMonster: In the 2019 anime, the [[spoiler:[[BigBad entity who controls Ryuuzouji]] is an extraterrestrial criminal who usurped the body of Eriko Takeda's lover, Abel, during their research on other dimensions. Slowly getting bored with Abel's body, he then brutally murders a man named Ryuuzouji and [[GrandTheftMe controls his body]]. To cover up his tracks, the entity then made up a curse by brutally murdering several innocent people. Taking an interest on a device known as Reflector Device that Kodai Arima and his son, Takuya, had, the entity then uses the powerful brainwashing power known as Niarb to control several people so that he could gain the device. Revealed to be one of the notable figures in another dimension known as Dela Granto, it was soon revealed that he manipulated the Great AI and the God Emperor for his own gains before being {{sealed|Evil In A Can}} by the latter. Escaping from his confinement, the entity then attempts to stop the ritual of Dela Granto which would [[OmnicidalManiac wipe out both Dela Granto and Earth]], and it's revealed that he has already destroyed 3 dimensions for his own amusement. When stopped, the entity then summons the ghosts from other dimensions to attack the innocent people in Dela Granto.]]
* CrossingTheLineTwice: In ''8-bit YU-NO's Big Adventure'', you can summon and ride Kun-Kun the friendly Nogard! What happens if you get hit? [[spoiler:She turns into a chicken leg that Yu-No can gleefully eat to gain back health, as a ''very'' BlackComedy-esque CallBack to the True route.]]
* InferredHolocaust: [[spoiler:Ayumi’s route strongly implies that Mio was trapped beneath Triangle Mountain just like in her own route. By the apparent mechanics of the Reflector and alternate dimensions, this means that Mio probably dies beneath Triangle Mountain in every route apart from her own, despite Takuya being the one to find a way out in her route, and only through what was functionally an illusion she didn't see. [[NoEndorHolocaust But hey, Mio does technically have an escape route so long as she doesn’t give up... right?]]]]
* ItWasHisSled: You'd be hard-pressed to find ''anywhere'' that doesn't consider the [[spoiler:second world]] to be something that isn't considered a spoiler, despite how much the VN hides it. Even the remake's opening completely spoils it!
* {{Moe}}: The titular Yu-No is absolutely adorable, [[spoiler:especially as a child.]]
* OnceOriginalNowCommon:
** This game has influenced so many later visual novels that nowadays, it's hard for most people to see why it was so groundbreaking. It's the first or one of the first in the medium to feature [[DoorStopper an epic-scale plot]], and the [[JigsawPuzzlePlot "multiple route mystery"]] structure, among others. In western countries, this is furthered by the fact that the game [[LateExportForYou didn't receive a translation until 2011]], long after many of its "imitators" were released for western audiences. One way this manifests itself is that in the Japanese visual novel database site Erogamescape, made largely of the original audience, it's rated much higher (at or near the top) than by Western visual novel readers at VNDB, though it has gotten some newfound appreciation after the remake got localized.
** The Visual Novel was released in 1996, ''well'' before the [[TrappedInAnotherWorld Isekai trend]] began in TheNewTens. However, the anime adaptation had the misfortune of airing in 2019, right when that fad was at its peak. Thus, some viewers who were thoroughly impressed with the Time Travel/Alternate Timeline thriller of the first half were puzzled and annoyed by the fact that the story suddenly shifted into yet another Isekai by the second half.
* PolishedPort:
** The UsefulNotes/SegaSaturn port. While it removed the H-Scenes, locked the protagonist's name to Takuya instead of [[HelloInsertNameHere letting the player input a custom name]], and has slightly worse audio quality, it added voice acting to most of the scenes. The voice cast is widely considered to be fantastic and to add a lot of power and emotion to most of the scenes, with some even straight-up calling it the best visual novel dub ever made. It also directly includes the originally fandisc-exclusive extra scenarios on the disc. Unfortunately, it suffered NoExportForYou, until...
*** The 2011 FanTranslation, which took the Windows version of the game (Considered to be a slightly inferior port to the PC-98 original) and turned it into a definitive edition of the original game. The voice acting from the Saturn version is ported over, as well as the extra scenarios; The H-scenes are also added back in, removing the censorship from the original Windows version, and the music tracks are ripped straight from the PC-98 rather than the Saturn, easily making it the best version to play the original game.
* PortingDisaster: The Windows version, while still playable, is considered to be the worst version of the game. The reasons for such are the censorship being much more awkwardly done in the 18+ [=CGs=], bizarre censoring of singular letters in character relationships (which spoils some twists by drawing attention to them), and a reduction in audio quality that wasn’t anywhere near as bad in the Saturn version.
* {{Squick}}: [[spoiler:Takuya makes a few creepy comments about Yu-No's body once they meet again in the Imperial Capital and he realizes that SheIsAllGrownUp. Later, after learning the truth about Dela Granto, they kiss, and, in the original version, have sex. ''[[ParentalIncest Yu-No has sex with her biological, blood-related father.]]]]''
* ThatOnePuzzle:
** In Mio's route, [[spoiler:underneath Triangle Mountain. You cannot proceed until you solve a somewhat tricky game of picross, which is very difficult for those who haven't solved any of them before. This is not made easier by the numbers being represented by made-up symbols instead. [[AntiFrustrationFeatures Fortunately, the remake eases this with an option allowing you to see the answer on the PDA outright. You just need to replicate it on the tomb.]]]]
** The jewel in Koudai's study. Most of the jewels are simply a case of being at a certain time in a certain route, but this one is locked inside a clock, and asks you to find a 2-number code to unlock it. Nowhere in any route is a code mentioned, leading to many players simply brute-forcing the puzzle. The only way to know about the code beforehand is also surprisingly obscure, and asks you to completely think outside the box. [[spoiler: Go and rewatch the game's [[https://www.youtube.com/watch?v=qGxwH6-_a7E introduction sequence]]. The code Koudai inputs is the one you need, [[MoonLogicPuzzle despite the main character never witnessing that in-universe]]. The remake doesn't even have the intro and instead, in the splash screen, shows the code as symbols flashing on the clock as the logo appears - this way of representing the information makes it even less obvious.]]
* UnintentionallyUnsympathetic: Yuuki, due to his treatment of Mio. On the surface, he cares for her, with his fawning over and accompanying her more than Takuya, but once you hear his interactions towards Mio’s love of archeology (of which she has dozens of notes on), he loses that sympathy. The reason? He clearly doesn’t give a single shit about it, as every time he blows her off (in a way that makes it clear he wasn’t even listening), and tries to convince her to do something else when she’s doing something involved with it[[note]]while she does often comment that Takuya would know what to do because his father was an archeologist and passed down some knowledge, she doesn’t know Yuuki is in love with her, so it’s purely innocent on her part[[/note]] nor consider learning about it so they can do it together. Even worse, Mio’s route has [[spoiler:him reveal something Mio told *Takuya* in confidence to the whole school, purely because Mio did something with Takuya instead of him, and which he only knows because he eavesdropped on their entire “date” at Triangle Mountain while doing archeology]]. The more you see them together, the more you realize he sees her not as a potential girlfriend, but a prize to be won.
* ValuesDissonance: Takuya's pervy, borderline creepy behavior towards the female cast might come off as very off-putting today (especially in the remake where it hasn't been toned down one bit) but it was actually a very common protagonist archetype for visual novels in 1996, since most visual novels at that time were PornWithoutPlot. Though unlike plenty of other examples from back then, Takuya was explicitly a generally good kid prior to his father dying, and his pervy, creepy behaviour is him trying to cope. It helps that the women he does it to either don't even give him attention for it, clearly pity him, or give him back just as good as he gives.
* {{Woolseyism}}: Attempted with [[spoiler:Celes']] name in the official remake translation. It has Takuya guess her name through English letters, rather than Japanese characters, despite the sounds him making not at all matching up the letters he guesses. While it's initially just an awkward case of localization, it completely crashes in its face when [[spoiler:her name is later revealed to be Sayless, and it simply ''sounds'' like Celes because of Japanese pronunciation]]. This changes a clever bit of wordplay into the character lying about her name for no reason and flies against her character.