* AscendedFanfic: Many official mutators and some gametypes are [[AscendedFanon inspired]] from several user-made content, thanks to the ease of [[GameMod modding]] ''VideoGame/UnrealTournament''. For example:
** Six out of nine maps from the Bonus Pack 2 are third-party maps. Four of the five new Assault maps were winners or runner-ups of the Phase IV Best Assault Map of the "Make Something Unreal" Contest.
** In addition, a few total conversion mods have become full titles of their own, such as ''VideoGame/AirBuccaneers'', ''VideoGame/RedOrchestra'' and ''VideoGame/KillingFloor''. ''VideoGame/AlienSwarm'' was also made into a freeware, standalone game, albeit converted to ''VideoGame/HalfLife2''[='=]s Source engine rather than staying with Unreal.
* CutSong: Two unused menu themes[[note]]The third one was reused for the single-player ladder intro cutscene[[/note]], the themes "Hell" and "Level 9"[[note]]which in ''2003'' were the theme songs for the maps [=DM-Curse3=] and [=CTF-DE-LavaGiant2=]; the former was replaced by [=DM-Curse4=] (which uses "Morpheus 3" as BGM) and the latter was cut without any replacement[[/note]], and "Onslaught 06".
* DummiedOut:
** There's a playable version of the Phoenix Bomber, which you usually call by using the Target Painter, unlockable via cheat. This version is called the Dragonfly.
** The Vehicle CTF gametype was technically finished when the game hit the stores, but has no official maps for it. As such, it's not playable in the Tournament and requires a custom map to play in Instant Action or multiplayer; there are plenty of those, however.
** There aren't official Assault maps featuring objectives which require the "use" key, even with the code being there since retail. Like above, there are plenty of custom maps that take advantage of it.
*** Furthermore, the announcer has an unused "Move onto the next objective" sound file which is not used in any official maps. This is also something custom maps make use of.
** By way of inheriting [=UT2003=]'s codebase, there's the original game's ladders.
** The game also includes the three voicepacks of ''VideoGame/UnrealChampionship'', which can be made available in-game with the right file edition.
* KeepCirculatingTheTapes: All ''Unreal'' games were de-listed by Epic and pulled from every single storefront in December 2022, so there's no legal way to obtain the game in any form.
* OfficialFanSubmittedContent: Most of the content of the Bonus Pack 2 is composed by entries of the "Make Something Unreal Contest". [=CTF-CBP2-Pistola=] won the Best Map award, while all of the Assault maps except [=AS-BP2-SubRosa=] were placed between 1º and 5º places in the Best Assault Map category. Of the Assault winners, only [=AS-MZ-HighRise=] didn't made it into the Bonus Pack 2.
* PromotedFanboy: [[PromotedFanboy/EpicGames Shares a page with the rest of Epic Games]].
* RefittedForSequel: The whole franchise has [[RefittedForSequel/{{Unreal}} its own page]].
* StaffCreatedFanWork:
** Chris "Plutonic" Blundell released an unfinished map called [[https://unrealarchive.org/maps/unreal-tournament-2004/onslaught/I/ons-icarus_72051797.html ONS-Icarus]] as a free addon. It was even mentioned as the first [[Awesome/VideoGameLevels "0wnage"]] map by lead designer Creator/CliffBleszinski.
** One map that didn't make the cut for the ECE bonus pack was ONS-Sidaro, as listed on [[http://www.hourences.com/portfolio/levels2.htm#Sidaro mapper Sjoerd De Jong (Hourences)'s portfolio]]. Hourences couldn't release the map to the public for free himself since he legally signed its rights away to Epic. Eventually in February 2021, about 16 years later, a Platform/{{Steam}} user [[https://steamcommunity.com/app/13230/discussions/0/3117024613284860616/ requested]] Epic to clear away the red tape. [[https://www.moddb.com/games/unreal-tournament-2004/addons/ons-sidaro They duly obliged.]]
* UpdatedRerelease: It should be noted that all of the upgrades and features available in the updated releases are also available as free downloads to owners of the original game. ''2004'' serves as a notable exception, where instead owners of ''2003'' were able to receive a discount on their purchase of the game.
** '''''Unreal Tournament 2004''''' towards ''VideoGame/UnrealTournament2003'': [=UT2003=] + its two Bonus Packs + extra content.
** ''2004'' itself has the '''''Editor's Choice Edition''''', which included several [[{{GameMod}} mods]] and the Editor's Choice Edition Bonus Pack, which was later released as another free Bonus Pack.
* WhatCouldHaveBeen: The whole franchise has [[WhatCouldHaveBeen/{{Unreal}} its own page]].
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