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U File - What is a .u file and how do I open it?
Learn about .U files and view a list of programs that open them.
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Overview
What is a U file? A U file is a class package used by Unreal Tournament and other games built with the Unreal Engine. It contains compiled UnrealScript classes and settings that define gameplay behavior, objects, and logic. U files are used to add various features, such as weapons, power-ups, AI behavior, or even full game modes.
More Information Developers and modders use tools provided by Epic Games, such as ucc.exe (Unreal Command Console), to compile their custom scripts into U files. Once compiled, users can distribute U files and drop them into the appropriate folder to modify or extend a game, similar to a plugin . For example, a modder might create a new weapon or character class in UnrealScript, compile it into a U file, and then load it into Unreal Tournament to use it during gameplay. U files are typically stored in the game's System folder (for example, \Unreal\System\ ). When a game launches, the engine loads the relevant U files from the System directory to access the necessary gameplay code.
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DeveloperN/A
Popularity2.7 | 7 Votes
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.U File Extension
3 file types use the .u file extension.
Unreal Tournament Class Package
| Developer | Epic Games |
| Popularity |
3.7 | 33 Votes |
What is a U file?
A U file is a class package used by Unreal Tournament and other games built with the Unreal Engine. It contains compiled UnrealScript classes and settings that define gameplay behavior, objects, and logic. U files are used to add various features, such as weapons, power-ups, AI behavior, or even full game modes.
More Information
Developers and modders use tools provided by Epic Games, such as ucc.exe (Unreal Command Console), to compile their custom scripts into U files. Once compiled, users can distribute U files and drop them into the appropriate folder to modify or extend a game, similar to a plugin . For example, a modder might create a new weapon or character class in UnrealScript, compile it into a U file, and then load it into Unreal Tournament to use it during gameplay.
U files are typically stored in the game's System folder (for example, \Unreal\System\ ). When a game launches, the engine loads the relevant U files from the System directory to access the necessary gameplay code.
How to open a U file
U files are not meant to be opened. Instead, the game packaged with the U file references it to load the information it stores.
However, gamers who enjoy modifying gameplay may extract and modify U files with tools, such as Dragon UnPACKer and Unreal Tournament Package Tool.
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Programs that open or reference U files
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Program Name
Platform
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X
Windows
Epic Games Unreal Tournament
Paid
Epic Games UnrealEd
Free
Dragon UnPACKer
Free
Unreal Tournament Package Tool
Free
Mac
Epic Games Unreal Tournament
Paid
Category: Game Files
Updated: May 1, 2025
AU Audio File
| Developer | N/A |
| Popularity |
3.3 | 9 Votes |
Audio container format typically used to store ?-law encoded audio data; introduced by Sun Microsystems and also used by MusicKit for the NeXT operating system; contains a header that includes six 32-bit words, an optional information section, then the audio data.
More Information
AU files typically use the .AU extension.
Programs that open U files
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Platform
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X
Windows
Microsoft Windows Media Player
Included with OS
Mac
Apple QuickTime Player
Included with OS
Category: Audio Files
Updated: March 27, 2014
Subsampled Raw YUV Image
| Developer | N/A |
| Popularity |
2.7 | 7 Votes |
Subsampled "U" image created by ppmtoyuvsplit, a Unix-based command-line utility that splits .PPM files into .Y , U, and .V files; contains the "U" chrominance, or color, component for the image; used for storing image data in a format required by the Stanford MPEG codec.
More Information
Y, U, and V files can be built back into their original PPM file using the yuvsplittoppm utility.
NOTE: The ppmtoyuvsplit and yuvsplittoppm programs are part of netpbm, a Unix-based graphics package.
Programs that open U files
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Platform
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Windows
Microsoft Windows Media Player with YUV Genius package
Included with OS
Mac
Apple QuickTime Player with QuickTime YUV codec
Included with OS
Linux
ppmtoyuvsplit
yuvsplittoppm
Category: Raster Image Files
Updated: May 26, 2010