How to View File Extensions

A file extension is the short suffix at the end of a filename that tells Windows and applications what type of file it is. The extension .png identifies a Portable Network Graphics image. The extension .dat identifies a data file. The extension .unity3d identifies a Unity asset bundle. By default, Windows hides these extensions in File Explorer, displaying only the part of the filename before the dot. For most computer users this default is acceptable. For Unturned™ mod developers it is dangerous, because mod assets are identified by their extension and an item file ending in .dat looks identical to a placeholder text file when extensions are hidden.

This article explains how to enable file extension display on Windows 10 and Windows 11, why every 57 Studios™ developer must do this on every workstation, and which extensions you will encounter daily in mod development.

The configuration takes approximately fifteen seconds and applies system-wide for the logged-in user. The benefit accumulates across every subsequent file operation: a modder with extensions visible can identify any file at a glance, while a modder with extensions hidden must repeatedly invoke right-click → Properties or rely on icon recognition that fails for files with no registered application.

Prerequisites

You must have File Explorer open. If you have not yet learned the launch methods, read How to Open File Explorer. You should also be comfortable navigating folders; if not, review How to Navigate to a Folder first.

What you will learn

• What a file extension is and why Windows hides it by default
• How to enable file extension display on Windows 11
• How to enable file extension display on Windows 10
• The extensions you will work with daily as an Unturned modder
• The serious risks of renaming extensions incorrectly
• How to register a new extension with a default application
• How to recognize disguised malicious files through extension awareness
• The historical reasons behind the hidden-extensions default

What a file extension actually is

A filename in Windows consists of two parts separated by a dot: the base name and the extension. In the filename Asset_Crate.png, the base name is Asset_Crate and the extension is .png. The extension can be any length, although most are between two and four characters.

Windows uses the extension to decide which application opens the file when you double-click it. This decision is called a file association and is stored in the Windows registry. The extension is the only thing that determines the association. Renaming photo.jpg to photo.png does not convert the file from JPEG to PNG; it only changes how Windows describes it.

Did you know?

The hidden extensions feature was introduced in Windows 95. The original intent was to protect novice users from accidentally renaming the extension and breaking the file. The side effect is that experienced users must enable extensions on every fresh install of Windows.

Extension length conventions

Most file extensions are three or four characters. The convention dates to the original MS-DOS 8.3 filename format, which allowed eight characters for the base name and three for the extension. Modern Windows file systems support arbitrarily long extensions (the file system itself imposes no length limit), but most applications and developers continue to use three- or four-character extensions for compatibility with older tools and conventions.

A small number of file types use longer extensions:

• .tar.gz (compound extension, common in archives)
• .unity3d (Unity asset bundle, seven characters)
• .config (XML configuration files)
• .html (web pages, four characters)
• .jpeg (alternative JPEG extension, four characters)

A few file types use compound extensions, where two extensions are concatenated to indicate multiple format layers. The most common is .tar.gz, which indicates a gzip-compressed tar archive. Windows treats the final extension as authoritative; tools like 7-Zip and tar interpret the compound extension correctly.

Case sensitivity of extensions

Windows file extensions are case-insensitive. IMAGE.PNG, image.png, Image.Png, and image.PNG all refer to the same extension. The case is preserved in the filename for display purposes but ignored when looking up file associations. Cohort modders typically write extensions in lowercase by convention, matching the practice on Unix-derived systems.

Best practice

Always write file extensions in lowercase. The case is ignored by Windows but is a strong cohort convention that improves readability across mixed Windows-and-Unix workflows. Mod project repositories shared between cohort members typically enforce lowercase extensions through documentation or pre-commit checks.

Why modders must always show extensions

Unturned™ mod development depends on extension awareness for three concrete reasons:

1. Many mod files share base names. A single item might consist of Crate.dat, Crate.unity3d, Crate.meta, and Crate_English.dat. Without extensions visible, all four appear as Crate, Crate, Crate, and Crate_English. You cannot tell them apart.

2. Renaming a file can destroy it. If you rename Crate.dat to Crate.txt thinking you are giving it a descriptive label, you have just changed its type. Unturned will no longer recognize it as an item definition.

3. Malicious files often hide their real extension. A file named mod_installer.png.exe looks like mod_installer.png when extensions are hidden, but it is actually an executable. Showing extensions reveals the true file type and protects you from disguised malware.

Critical warning

Never download and run an executable that pretends to be an image, document, or audio file. If you see .exe at the end of a filename in a folder labeled "textures" or "models", do not open it. Real mod assets are never executables.

The three reasons above are documented across cohort experience as the most frequent causes of mod-development errors caused by hidden extensions. A modder who has extensions visible from the start avoids all three failure modes. A modder who waits to enable extensions until after a failure has typically already lost time to one or more of them.

The cohort recommendation: enable on day one

The cohort-recommended workflow is to enable file extensions on every fresh Windows installation, before any other file-management activity. The configuration is one of the first steps in the cohort's standard Windows onboarding checklist. Modders who skip this step report consistently higher rates of mod-build errors caused by mis-identified files in their first weeks of mod work.

Best practice

Add "Enable file extensions" to your fresh-install checklist for Windows workstations. The configuration takes fifteen seconds and prevents an entire class of file-management errors. Cohort modders who maintain such a checklist report consistently faster ramp-up times on new workstations.

Enabling extensions on Windows 11

Windows 11 simplified the File Explorer interface. The View settings now live under a single View button in the command bar.

1. Open File Explorer.
2. Click the View button in the command bar at the top of the window.
3. Hover over Show.
4. A submenu appears. Click File name extensions to toggle it on.

A check mark appears next to File name extensions when the setting is enabled. Every file in every folder now displays its extension immediately.

Pro tip

The same submenu contains Hidden items, which you should also enable. The next article covers hidden items in detail. Enable both at the same time to save a trip back to this menu.

The Windows 11 implementation toggles the extension display globally for the current user. The setting is stored in the registry at HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\HideFileExt. A value of 0 shows extensions; a value of 1 hides them. Cohort modders who manage many workstations sometimes set this registry value through PowerShell or Group Policy to ensure consistency across their fleet.

Did you know?

The Windows 11 View → Show submenu organizes all visibility-related settings into a single location. Earlier Windows versions scattered these settings across the ribbon, Folder Options, and View menus. The consolidation is one of the more useful Windows 11 interface improvements.

Enabling extensions on Windows 10

Windows 10 uses the older ribbon interface. The setting lives in a different location.

1. Open File Explorer.
2. Click the View tab in the ribbon at the top.
3. In the Show/hide group on the right side of the ribbon, find the File name extensions checkbox.
4. Click the checkbox to enable it.

The setting takes effect immediately. Every file now displays its extension.

If your Windows 10 installation does not show the ribbon, you can enable extensions through Folder Options instead:

1. Open File Explorer.
2. Click File in the upper left, then Change folder and search options.
3. In the Folder Options dialog, click the View tab.
4. Scroll down to Hide extensions for known file types and uncheck it.
5. Click Apply, then OK.

The two methods produce the same outcome: the registry value HideFileExt is set to 0 and File Explorer begins displaying extensions immediately. The Folder Options method is useful when the ribbon is hidden, when scripting the configuration across multiple workstations, or when teaching the configuration to users who prefer dialog-based interfaces.

Best practice

Cohort modders who manage Windows 10 workstations alongside Windows 11 workstations should document both paths in their onboarding materials. The two operating systems behave the same once the setting is enabled, but the paths to enable it differ.

Comparison of Windows 10 and Windows 11 steps

Step	Windows 10	Windows 11
Entry point	View tab in ribbon	View button in command bar
Menu depth	One click	Two clicks (View → Show)
Setting label	File name extensions	File name extensions
Alternative path	File → Change folder and search options → View tab	Three-dot menu → Options → View tab
Persistence	Per user, all folders	Per user, all folders
Registry key	HKCU...\Advanced\HideFileExt	HKCU...\Advanced\HideFileExt
Group Policy support	Yes	Yes
Default value	Hidden (HideFileExt=1)	Hidden (HideFileExt=1)

The setting persists across reboots, but it is per-user. If you set up a new user account on the same computer, you must enable extensions again for that account.

Extensions every modder works with daily

Extension	Format	Used for	Opens with
.dat	Plain text key-value	Item, vehicle, NPC definitions	Notepad++
.png	Image	Textures, icons, screenshots	Photos, Paint, Krita
.jpg / .jpeg	Image	Photos, reference art	Photos
.unity3d	Unity asset bundle	3D models, materials, prefabs	Unturned at runtime
.meta	Unity metadata	GUIDs and import settings	Notepad++
.json	Structured text data	Configuration, manifest	Notepad++
.txt	Plain text	Notes, readme, changelog	Notepad++
.zip	Archive	Distribution of mod folders	7-Zip, Windows
.rar	Archive	Older mod distributions	7-Zip
.psd	Photoshop document	Layered texture source	Photoshop
.fbx	3D model	Importing into Unity Editor	Unity, Blender
.blend	Blender file	3D modeling source	Blender
.cs	C# source code	Plugin scripts	Notepad++, Visual Studio
.dll	Compiled library	Plugin assemblies	Loaded by Unturned
.xcf	GIMP document	Layered raster source	GIMP
.tga	Targa image	Legacy texture format	Photoshop, Krita
.tif / .tiff	TIFF image	High-bit-depth textures	Photoshop
.exr	OpenEXR image	HDR textures	Photoshop, Krita
.wav	Audio	Sound effects	Audacity
.ogg	Compressed audio	Game audio	Audacity
.mp3	Compressed audio	Music	Audacity
.xml	Structured text	Configuration	Notepad++
.yaml / .yml	Structured text	Modern configuration	Notepad++
.md	Markdown	Documentation	Notepad++
.bat	Batch script	Windows automation	Notepad++
.ps1	PowerShell script	Modern Windows automation	Notepad++, PowerShell ISE

Memorize the first ten. They cover more than ninety percent of mod files you will touch. The remaining extensions appear in specific contexts (audio, scripting, advanced asset formats) and can be learned as the workflow demands.

Extension visual recognition

Cohort modders develop visual recognition for the most common extensions over the first few months of mod work. The recognition is automatic enough that experienced modders can scan a folder of 50 files and instantly identify the category of each file without reading the extensions deliberately. The skill takes approximately three months to develop and depends on extensions being visible during that learning window.

Best practice

Set Notepad++ as the default application for .dat, .meta, .json, .txt, .xml, .yaml, and .md files. These are the seven most common text-based formats in mod development, and Notepad++ handles them all better than the default Notepad.

Renaming extensions: when and why

The general rule for beginners is that you do not rename extensions. The extension reflects the file's contents, and changing the extension does not change the contents. Renaming Crate.dat to Crate.txt does not convert it.

There are three legitimate situations where renaming an extension is correct:

1. Correcting a typo in a freshly created file. If you created Crate.dta instead of Crate.dat, renaming is appropriate because the contents are still correct text data.
2. Adding a clarifying extension to an extensionless file. Some old mod archives contain files with no extension. Adding the correct extension based on the contents is appropriate.
3. Forcing a different application to handle a file. Renaming script.cs to script.txt will cause Notepad to open it instead of Visual Studio. This is occasionally useful for quick read-only viewing.

Common mistake

A new modder sees Crate.dat in their project folder and renames it to Crate.dat.txt because Notepad keeps appending .txt automatically. The result is a file Unturned no longer recognizes. The fix is to remove the trailing .txt. The prevention is to enable extensions and always type the full filename including extension when saving.

Conversion versus renaming

Cohort modders new to the platform sometimes attempt to convert a file format by renaming the extension. This never works: the extension is a label, not a transformation. To actually convert a file format, use a dedicated conversion tool:

• Image conversion: Photoshop, Krita, GIMP, ImageMagick (command line), Paint.NET
• Audio conversion: Audacity, ffmpeg (command line)
• Document conversion: LibreOffice, Pandoc (command line)
• 3D model conversion: Blender, Unity Editor

Each tool reads the source file in its native format, transforms it through application-specific logic, and writes the destination file in the target format. The destination file is a new file with the correct contents and the correct extension. The source file is unchanged.

Did you know?

The cohort's most-cited image conversion command is magick input.psd output.png (using ImageMagick), which flattens a Photoshop document and writes it as a PNG. The command is part of many cohort modders' standard texture-export pipeline.

Default applications and extension associations

When you enable extensions, you will often notice that some files do not show a meaningful icon. This is because no application is registered to handle the extension.

To register a default application:

1. Right-click any file with the unregistered extension.
2. Choose Open with.
3. If the application you want is in the list, click it. Otherwise click Choose another app.
4. Select the application.
5. Check the box labeled Always use this app to open .ext files.
6. Click OK.

From now on, double-clicking any file with that extension opens the chosen application.

Best practice

Register Notepad++ as the default for .dat, .meta, .json, and .txt files. These are the four most common text-based formats in mod development, and Notepad++ handles them all far better than the default Notepad.

The Settings → Apps → Default apps interface

For bulk configuration of default applications, the Settings interface provides a per-extension and per-application view:

1. Press Windows + I to open Settings.
2. Navigate to Apps → Default apps.
3. Choose an extension or an application.
4. Set the default association.

The Settings interface is the cohort-recommended method when configuring many extensions at once on a fresh workstation. The right-click → Open with method is faster for one-off changes.

Pro tip

On a fresh workstation, immediately after installing Notepad++, register it as the default application for all common text-based mod-development extensions. The bulk registration takes approximately three minutes through Settings → Apps → Default apps and pays back in faster file-opening across every subsequent mod work session.

Frequently asked questions

Why does my filename show two dots, like Crate.dat.txt?

Because you renamed it incorrectly or your text editor appended .txt automatically. The actual extension is the part after the last dot. Rename the file and remove the trailing .txt.

Can a file have no extension at all?

Yes. Some configuration files use no extension (such as LICENSE or README). Windows still tracks them, but no application is associated by default. Use right-click and Open with to choose how to open them.

Why are some extensions still hidden even after enabling the setting?

A few system file types, notably .lnk shortcuts, remain hidden even with extensions enabled. This is a special-case behavior that cannot be changed through File Explorer settings. The behavior is documented in the Windows registry under HKCR\lnkfile\NeverShowExt.

Does enabling extensions change how files behave?

No. Enabling extension display is a pure visual change. The files themselves are unchanged, and applications continue to handle them in exactly the same way. The only thing that changes is whether the extension is visible in File Explorer.

Can I show extensions only for certain folders?

No. The extension display setting is global per user. There is no per-folder override. Cohort modders who want different display settings for different folders must rely on Folder Options' Apply to Folders / Reset Folders behavior, which controls view settings but not the global extension toggle.

Why does Windows hide extensions by default?

Microsoft introduced the hidden-extensions default in Windows 95 to protect novice users from accidentally renaming extensions and breaking files. The protection trade-off is that experienced users (cohort modders included) must enable extensions on every fresh installation. The default has not changed in thirty years despite repeated user feedback because Microsoft considers the protection still valuable for typical home users.

How do I show extensions on a Windows Server installation?

The procedure is the same as on Windows 10 or Windows 11. Open File Explorer, navigate to View settings, enable file name extensions. The setting is per-user on Windows Server just as on client Windows.

Can extension display be configured through Group Policy?

Yes. The relevant Group Policy setting is at User Configuration → Administrative Templates → Windows Components → File Explorer → Hide extensions for known file types. Setting the policy to Disabled forces extensions to be shown. Cohort modders who manage many workstations centrally typically configure this through Group Policy.

Why are some extensions displayed in all uppercase?

The case shown in the file list matches the case as stored in the file system. A file created or copied with an uppercase extension displays the extension in uppercase. To normalize case, rename the file with the desired case. The cohort convention is lowercase extensions.

Can I see the extension of a file in a different way without enabling the global setting?

Yes. Right-click the file → Properties → General tab. The Type and File Type fields show the extension and the registered file type description. This per-file inspection works regardless of the global extension display setting.

Does the macOS Finder behave the same as File Explorer with extensions?

macOS Finder hides extensions by default but offers per-file extension display through Get Info. The global toggle in Finder Preferences → Advanced → "Show all filename extensions" matches File Explorer's global setting. Cohort modders who maintain both Windows and macOS workstations should enable extension display globally on both.

Do file extensions matter in PowerShell or Command Prompt?

Yes. PowerShell and Command Prompt use extensions to identify executable files (the PATHEXT environment variable lists the executable extensions, default: .com;.exe;.bat;.cmd;.ps1). The extensions matter for the shell's own behavior even when the user is not visually identifying files. Cohort modders should be aware of PATHEXT if they write scripts that launch other executables.

Best practices

• Enable file extensions on every Windows installation, immediately, before doing any mod work.
• Register Notepad++ as the default application for .dat, .meta, .json, and .txt.
• When creating new files, always type the complete filename including extension to avoid the dual-extension trap.
• Never trust an icon. Always read the extension to confirm what a file actually is.
• Write extensions in lowercase by convention, matching cohort and Unix practice.
• Use a real converter application when you need to convert between formats; never rely on renaming.
• Enable extensions through Group Policy when managing multiple workstations centrally.
• Inspect file Properties when a file's extension is suspicious or unfamiliar.
• Add the extension configuration step to your fresh-install checklist for Windows workstations.

Appendix A: extension-by-category reference

The following table organizes the mod-development extensions by category and documents the cohort-recommended default application for each.

Image extensions

Extension	Format	Recommended app
.png	Portable Network Graphics	Krita
.jpg / .jpeg	JPEG	Photos
.bmp	Windows Bitmap	Paint
.gif	Graphics Interchange Format	Photos
.tga	Targa	Photoshop
.tif / .tiff	Tagged Image File Format	Photoshop
.exr	OpenEXR	Photoshop
.webp	Google WebP	Photos
.svg	Scalable Vector Graphics	Inkscape
.psd	Photoshop Document	Photoshop
.xcf	GIMP native	GIMP
.kra	Krita native	Krita
.ai	Adobe Illustrator	Illustrator

Audio extensions

Extension	Format	Recommended app
.wav	Uncompressed PCM audio	Audacity
.mp3	MPEG-1 Audio Layer III	Audacity
.ogg	Ogg Vorbis	Audacity
.flac	Free Lossless Audio Codec	Audacity
.aac	Advanced Audio Coding	Audacity
.m4a	MPEG-4 Audio	Audacity
.wma	Windows Media Audio	Audacity

Text and data extensions

Extension	Format	Recommended app
.txt	Plain text	Notepad++
.dat	Unturned data file	Notepad++
.json	JavaScript Object Notation	Notepad++
.xml	Extensible Markup Language	Notepad++
.yaml / .yml	YAML	Notepad++
.toml	TOM's Obvious Minimal Language	Notepad++
.ini	Configuration file	Notepad++
.csv	Comma-separated values	Notepad++
.tsv	Tab-separated values	Notepad++
.md	Markdown	Notepad++
.log	Log file	Notepad++
.cfg	Configuration file	Notepad++
.meta	Unity metadata	Notepad++

Code extensions

Extension	Format	Recommended app
.cs	C# source	Notepad++ or Visual Studio
.cpp / .h	C++ source / header	Notepad++ or Visual Studio
.py	Python source	Notepad++
.js	JavaScript	Notepad++
.ts	TypeScript	Notepad++
.html	HTML	Notepad++
.css	Cascading Style Sheets	Notepad++
.bat	Batch script	Notepad++
.ps1	PowerShell script	Notepad++ or PowerShell ISE
.sh	Shell script	Notepad++

Archive extensions

Extension	Format	Recommended app
.zip	ZIP archive	7-Zip
.7z	7-Zip archive	7-Zip
.rar	RAR archive	7-Zip
.tar	TAR archive	7-Zip
.gz	GZip compressed	7-Zip
.bz2	BZip2 compressed	7-Zip
.iso	ISO disc image	7-Zip

3D and Unity extensions

Extension	Format	Recommended app
.fbx	Autodesk FBX	Blender
.obj	Wavefront OBJ	Blender
.blend	Blender native	Blender
.3ds	3D Studio	Blender
.dae	COLLADA	Blender
.unity	Unity scene	Unity Editor
.unity3d	Unity asset bundle	Loaded by Unturned at runtime
.prefab	Unity prefab	Unity Editor
.mat	Unity material	Unity Editor
.asset	Unity asset	Unity Editor

Executable and library extensions

Extension	Format	Recommended app
.exe	Windows executable	Do not open from untrusted sources
.dll	Dynamic-link library	Loaded by other applications
.msi	Windows Installer	Windows Installer
.com	DOS command (legacy)	Avoid

Appendix B: detecting disguised malicious files

The hidden-extension default creates a documented attack vector: a malicious file can use a deceptive base name that includes a fake extension, hiding its true executable extension behind the disabled display.

The classic pattern:

Filename as displayed (extensions hidden):  mod_installer.png
Filename actually written to disk:          mod_installer.png.exe

When extensions are hidden, the user sees what appears to be a PNG image. Double-clicking the file launches the executable, which can install malware, steal credentials, or take other malicious action.

The cohort's recommended detection protocol:

1. Enable extensions globally. This single configuration step exposes the deception immediately.
2. Inspect Properties. Right-click any suspicious file → Properties. The Type field shows the actual file type.
3. Check the file's source. Files from official cohort or 57 Studios distribution channels are trustworthy. Files from random Discord servers, untracked downloads, or shared drives should be inspected carefully.
4. Use Windows Defender or a third-party antivirus. Real-time scanning catches most disguised malware before it executes.
5. Verify file hashes for distributed mods. Cohort distribution channels publish SHA-256 hashes for verified mod releases. Verify the hash before running any executable installer.

Critical warning

A file with an executable extension (.exe, .bat, .ps1, .com, .msi, .scr, .cmd, .vbs, .js, .jar, .hta) downloaded from an untrusted source should never be opened. Real mod assets are not executables. If you receive a file with these extensions in a mod-related context, treat it as suspicious until proven otherwise.

Appendix C: registry and Group Policy reference

For cohort modders who manage workstations through scripting or central administration, the following registry and Group Policy locations control extension display.

Registry value

Path	Value name	Type	Setting
HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced	HideFileExt	DWORD	0 to show, 1 to hide

Group Policy

• Path: User Configuration → Administrative Templates → Windows Components → File Explorer
• Policy: "Hide extensions for known file types"
• States: Not Configured (default), Enabled (force hide), Disabled (force show)

PowerShell to enable extensions

Set-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced' -Name 'HideFileExt' -Value 0
Stop-Process -Name explorer -Force

The script sets the registry value and restarts File Explorer to apply the change immediately. Cohort modders who configure workstations through PowerShell can include this snippet in their onboarding script.

Best practice

Maintain a PowerShell onboarding script for fresh Windows workstations. The script enables file extensions, hidden items, and other cohort-recommended configurations in a single execution. Cohort modders who maintain such a script report fresh-install ramp-up times measured in minutes rather than hours.

Appendix D: extension usage frequency among cohort modders

The cohort has tracked extension exposure across thousands of mod-development sessions. The following pie chart documents the relative frequency of extension types encountered during typical work sessions.

Text and data extensions dominate cohort exposure because most mod development involves editing configuration files, item definitions, and asset metadata. Image extensions are the second-most-encountered category because every mod requires texture work. The dominance of these two categories explains the cohort recommendation to register Notepad++ and Krita (or Photoshop) as the primary default applications on every workstation.

Did you know?

The extension exposure dataset began collection in 2023 and now includes data from approximately 800 active cohort modders. The dataset informs the cohort's recommended default application configurations and the priority order for the extension reference tables in this article.

Appendix E: extension migration patterns

Cohort modders occasionally need to migrate large numbers of files between extension conventions. The following patterns document the cohort-recommended approaches.

Pattern 1: convert PSD source files to PNG distribution files

A modder maintains layered Photoshop files for texture sources but distributes flat PNG files in mod bundles. The cohort-recommended pattern is to use a build script that exports each PSD to a corresponding PNG at bundle time.

Get-ChildItem -Path .\Sources -Filter *.psd | ForEach-Object {
    $destination = $_.FullName -replace '\.psd$', '.png' -replace 'Sources', 'Bundles'
    magick convert $_.FullName -flatten $destination
}

The script reads each PSD, flattens its layers, and writes a PNG to the parallel Bundles folder. The pattern preserves the layered source files while producing the flat distribution files the mod ships with.

Pattern 2: rename files with uppercase extensions to lowercase

Some legacy mod archives contain files with uppercase extensions (.PNG, .JPG, .DAT). To normalize to the cohort lowercase convention:

Get-ChildItem -Path . -Recurse | Where-Object { $_.Extension -cne $_.Extension.ToLower() } | Rename-Item -NewName { $_.Name -replace ($_.Extension), $_.Extension.ToLower() }

The script finds all files where the extension is not already lowercase and renames them. Cohort modders running this on inherited project trees report consistent cleanup of legacy case-mixing.

Pattern 3: add missing extensions to extensionless files

Some legacy archives contain files with no extension. To add an appropriate extension based on file content:

Get-ChildItem -Path . | Where-Object { -not $_.Extension } | ForEach-Object {
    $bytes = Get-Content $_.FullName -Encoding Byte -TotalCount 4
    if ($bytes[0] -eq 0x89 -and $bytes[1] -eq 0x50) {
        Rename-Item $_.FullName -NewName "$($_.Name).png"
    }
    # Additional file-signature checks would go here
}

The script reads the first four bytes of each extensionless file and adds the appropriate extension based on file signatures. The script can be extended to detect JPEG, GIF, ZIP, and other common file types.

Best practice

Test migration scripts on a copy of the project tree before running on the original. Renaming operations are typically reversible (right-click → Properties → Previous Versions can restore the original name), but a backup is faster than relying on Windows' version-history feature.

Appendix F: extension and content mismatch

A file's extension and its actual contents can become mismatched in several documented scenarios. Cohort modders should recognize and resolve these scenarios when they occur.

Scenario A: file renamed with wrong extension

A modder renames Crate.dat to Crate.json without changing the contents. The file still contains Unturned's key-value format, but applications opening it as JSON will fail to parse it.

Resolution: Rename back to .dat. The contents are unchanged; only the extension was wrong.

Scenario B: file copied from another system with stripped extension

A file copied through certain network protocols or mail attachments may arrive without its original extension. The file's contents are intact but Windows cannot identify the file type.

Resolution: Inspect the file with Notepad++ or a hex viewer. The first few bytes (the file signature) identify the actual format. Add the correct extension.

Scenario C: file generated by a tool with non-standard extension

Some tools produce output files with idiosyncratic extensions (.bak, .tmp, .out). The contents may be a standard format with a non-standard wrapper.

Resolution: Open the file with Notepad++ to inspect contents. If the contents are a recognizable format, rename to the standard extension. If the contents are binary, use a hex viewer to identify the file signature.

Scenario D: archive extracted to a wrong-extension file

Some archive formats can produce output files with unexpected extensions. The file is correctly formatted but the extension does not match the user's expectation.

Resolution: Verify the archive's extraction settings. Most archive tools preserve the original filenames stored in the archive metadata; the extension mismatch typically indicates a tool configuration issue rather than a corrupted file.

Scenario E: file with double extension

A file named Crate.dat.txt has two extensions. The file system treats the final extension as authoritative (.txt). Some applications may try to interpret the file as the inner extension's format.

Resolution: Decide which extension is correct. If the file is actually Unturned data, remove .txt to leave Crate.dat. If the file is actually text, remove .dat to leave Crate.txt.

Common mistake

Confusing the cause of a "wrong app opens this file" problem. The cause is almost always the extension, not the file's contents. Inspect the extension first; only after verifying the extension should you suspect the file's contents.

Document history

Version	Date	Notes
1.0	2024-09-10	Initial publication. Windows 10 and Windows 11 paths documented.
1.1	2024-11-22	Added extension reference table. Expanded renaming guidance.
1.2	2025-01-30	Added default applications section. Added decision flowchart for renaming.
2.0	2025-03-12	Major revision. Added extension-by-category reference, malicious file detection protocol, and registry/Group Policy reference.
2.1	2025-05-17	Annual refresh. Added conversion versus renaming section, case sensitivity guidance, and PowerShell onboarding snippet.

Appendix G: extension troubleshooting reference

The following table documents the most common extension-related problems and their resolutions. Cohort modders should refer to this table when encountering unexpected file behavior.

Symptom	Likely cause	Resolution
Wrong application opens a file	Default association set incorrectly	Right-click → Open with → Choose another app → Always use this app
Application reports "unknown format"	Extension does not match contents	Verify contents with Notepad++; rename extension to match
File icon shows blank or generic	No application registered for extension	Right-click → Open with → Choose another app
Double-click does nothing	No default association	Settings → Apps → Default apps → set association
File appears twice in folder listings	View setting issue, not duplicate file	View → Show → uncheck Item check boxes
Cannot rename extension	File is open in an application	Close the application first
Rename adds extension automatically	Notepad's "Save as type" appended .txt	In Save dialog, change "Save as type" to "All Files"
Extension visible in some folders but not others	View applied per-folder not globally	View → Show → File name extensions in any folder applies globally
Files with same name but different extensions sorted oddly	Sort by Name versus Type	Click Type column header to group by extension
Antivirus quarantines a .dat file	False positive	Verify file's source; add exception if trusted
Extension changes silently	Application's "Save as" appended a different extension	Watch the Save dialog's filename field carefully
Extension display reverts after reboot	User profile corruption	Re-enable through View; if recurring, check Group Policy

Appendix H: cohort onboarding script

The cohort's reference onboarding script for new modders' fresh Windows workstations includes file-extension configuration as one of the first executed steps. The relevant script section:

# Enable file extensions
Set-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced' -Name 'HideFileExt' -Value 0

# Enable hidden items
Set-ItemProperty -Path 'HKCU:\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced' -Name 'Hidden' -Value 1

# Set default app for .dat to Notepad++
$nppPath = 'C:\Program Files\Notepad++\notepad++.exe'
if (Test-Path $nppPath) {
    # Register file association via reg edits or SetUserFTA tool
}

# Restart File Explorer to apply changes
Stop-Process -Name explorer -Force
Start-Process explorer.exe

The script can be expanded with additional cohort-recommended configurations: default app registrations, Quick Access pins, and View settings normalization. Cohort modders who maintain such scripts report fresh-workstation setup times of approximately five minutes versus several hours for manual configuration.

Did you know?

The cohort's onboarding script library includes scripts for Windows, macOS, and Linux. The cross-platform coverage supports cohort modders who maintain multiple workstation environments. The scripts are version-controlled and updated periodically as Windows changes its registry layout or default behaviors.

Cross-references

• How to Open File Explorer — the prerequisite skill for accessing the View menu where the extension toggle lives.
• How to Navigate to a Folder — the navigation foundation that lets you reach the folders where you will inspect files.
• How to View Hidden Files — the next configuration step; typically enabled at the same time as extensions.

Next steps

With extensions visible, the next configuration step is making hidden files and folders visible. Many important mod-related folders are hidden by default. Continue to How to View Hidden Files to enable this setting.

Enabling file extensions is one of the highest-leverage configuration changes a Windows mod developer makes. The setting takes fifteen seconds to enable, applies system-wide, and prevents an entire category of file-management errors for the lifetime of the workstation. Cohort modders who treat this step as mandatory on every fresh install report measurably fewer file-identification errors across their careers.

Did you know?

The cohort's documented "first month error rate" for new modders correlates strongly with whether the modder enabled file extensions in week one. Modders who enable extensions on day one report approximately one-quarter the rate of file-identification errors of modders who delay the configuration. The single configuration change is the most predictive single behavior in the cohort's onboarding telemetry.

Pro tip

After enabling extensions, take a quick tour of your mod project folder. You will notice file types you previously could not distinguish. Spend ten minutes inspecting the files visually to build the recognition reflex that makes extension awareness reflexive within a few weeks.

Best practice

Combine the extension-display configuration with the hidden-items configuration covered in the next article. The two settings live in the same View → Show submenu on Windows 11, and toggling both at once saves a trip back to the menu later. Cohort modders treat the two settings as a single configuration step.

Common mistake

Believing that enabling extensions has changed the behavior of your files. The configuration is purely visual. Applications, scripts, and the file system itself behave identically before and after the configuration; only the display changes. If a file's behavior changed at the same time as you enabled extensions, the cause is unrelated and should be investigated separately.

Did you know?

A cohort modder who skipped the extension-display configuration on a new workstation lost approximately four hours of work in their first week to a misidentified file: they treated a .dat.txt file as a working item definition and wondered why Unturned would not load it. The fix took thirty seconds once they enabled extensions. The cohort cites this case study as the operational reason behind the day-one configuration recommendation.

Pro tip

Pair the extension configuration with the hidden-items configuration in a single fifteen-second session at the start of any fresh Windows installation. The two settings together cover the full visibility configuration cohort modders need for productive mod work. Reaching for the View → Show submenu twice in quick succession (once for each toggle) becomes a reflex within a few workstation setups.

Best practice

After completing the configuration on a fresh workstation, navigate to an Unturned mod project folder and verify that file extensions are visible across files of multiple types. The verification step confirms that the configuration took effect and exposes any per-folder view overrides that might still be hiding extensions in specific locations.