History ShoutOut / Omori

*** Headspace is basically a WholePlotReference to the first two games' Magicant, a surreal dreamscape that exists inside its ruler's head. In the first game, [[spoiler: its existence hides a secret behind Queen Mary's past, like how Headspace was made to hide a secret from Sunny's past.]] In the second game, [[spoiler: Ness faces the evil within himself in Magicant, like how Sunny faces Omori, who represents the trauma and self-hatred he feels from accidentally killing Mari, inside Whitespace.]]

*** [[spoiler: The final boss battle involves an unbeatable enemy with the background becoming increasingly distorted and disturbing as the battle goes on.]]

*** Faraway Town has a cat named Claus and a dog named Lucas. An obvious reference to Claus and Lucas from Mother 3.

** The first room the player character enters after leaving the starting area has a tv showcasing a movie where four boys walk along a set of railroad tracks, much like in Red, Blue, and their remakes. As in the original, this referred to ''Film/StandByMe''.
** In [[spoiler:Last Resort]], you can access [[spoiler:the concierge area]] if you give the guard some bottled water, just like you could gain access to Saffron City in Red, Blue and Yellow if you give one of the guards some fresh water (it was changed to tea in the remakes).

** [[spoiler:The entirety of the Black Space and Black Space 2 areas is essentially a Yume Nikki fangame.]]
** [[spoiler:The Bad Ending has Omori, now in [[SplitPersonalityTakeover control of Sunny's body]], jump off the edge of a building, not unlike Yume Nikki's ending.]]

** [[spoiler:Just like the three secret areas with the empty boxes, Black Space 2 unlocks more secret areas that were previously unavailable in the Main Route, with each area being more disturbing and horrifying than the other. And just like ''.flow'', the player is forced to do something with the Dream World in order to unlock said secret areas.]]

** The [[HelloInsertNameHere naming system]] will disallow names already taken by important characters, including even Omori himself, who's supposed to be the PlayerCharacter. And similar to the big twist of ''Undertale'', anyone who's played it may figure out ahead of schedule that you're not naming the character you thought you were. [[note]]This may also be a reference to VideoGame/EarthboundBeginnings which also disallows you to name any of the characters after important characters.[[/note]]
** Related to the above, the FinalBoss is [[spoiler: Omori himself in a BattleInTheCenterOfTheMind. While no such battle takes place in ''Undertale'', comparisons between Omori and the Fallen Child are otherwise not hard to draw]].
** There are secret events that can only be seen by modifying the WTF value to certain numbers during the Main Route [[spoiler:and the Hikikomori Route]], just like the "fun" value in ''Undertale''. In addition, the character of [[spoiler:[[RetGone W.D. Gaster]]]] is somewhat similar to [[spoiler:Abbi, who was also effectively erased from the game world with only a few remnants of her existence]], and the [[spoiler:three Gaster Followers]] are paralleled with the [[spoiler:three Beta Characters (Uni, Tako, Meido) in Black Space]].

** The theme for the fight against Pluto[[spoiler:'s Expanded form]] is called [[VisualNovel/UminekoWhenTheyCry GOLDENVENGEANCE]]. Similarly, Sweetheart's boss theme is titled World's End Valentine. Both songs are named in a similar way to certain songs in ''Umineko'', specifically GOLDENSLAUGHTERER (among other songs that have two words in all caps and without a space) and World End Dominator. Both songs also wouldn't feel out of place if they played in ''Umineko''.
** Rococo's fourth commission is an anime-style rendition of the main group titled "[[Manga/JoJosBizarreAdventure Omori's Unusual Escapades]]".
** The battle against The Maverick has him mention his "final form" and, at the end of the fight, he tries to use a Spirit Bomb as his finishing move, both of which are from ''Anime/DragonBallZ''.

** Sunny winds up having the same trajectory as the main character from ''Manga/GoodnightPunpun'', where [[spoiler: both are left with eye injuries and are contemplating suicide in response to everything that's happened with them; though, unlike Punpun, Sunny has the option to successfully go through with it.]]
** [[spoiler:Mari's hanging corpse]], with her huge mass of long hair covering everything but a single unblinking eye, is a dead ringer for [[Literature/TheRing Sadako.]]

** The description for the Star Fruit Soda says that it's meant to be shared with a friend, similar to the local legends about the star-shaped Paopu Fruit in ''Franchise/KingdomHearts''.