How to set up a custom cursor and icons in the MU client

Small details are what separate an amateur client from one that looks like a serious server. The mouse cursor inside the game, the taskbar icon, the desktop shortcut icon and the in-game system icons (shop, events, hotkeys) form a continuous visual identity — from the moment the player clicks the shortcut to when they're hunting in Lorencia. This guide shows, in practice, how to swap each of these elements, which formats to use and how not to break the client in the process. It's an intermediate-level tutorial: you'll work with MU textures and executable resources, but without risky byte editing.

Prerequisites

• Your server's client already built and working. If you're still setting up the server itself, first see the guide on how to set up a MU Online server.
• An image editor with transparency support: GIMP (free) or Photoshop.
• A MU texture converter (.ozj/.ozt) compatible with your season.
• Resource Hacker (free) to edit the icon embedded in Main.exe.
• IcoFX, GIMP or an online converter to generate .ico files with multiple sizes.
• (Optional) ImageMagick to generate .ico from the command line.
• A backup of the client's texture folder and of Main.exe.

Understand the client's three different "icons"

Many people lump it all into one, but there are three distinct things, each edited in its own way:

The mental rule: if it appears inside the game, it's a texture; if it appears in Windows (taskbar, Explorer), it's an .exe resource.

How the MU cursor works

In most versions, MU Online draws its own mouse pointer as a texture, hiding the Windows cursor while the game is in focus. This has two implications:

1. You change the cursor by editing a client texture file, not the Windows mouse settings;
2. The cursor texture usually has transparency (the pointer isn't a rectangle), so it's normally .ozt (TGA base with an alpha channel).

Swap the in-game cursor (step by step)

1. Locate the cursor texture in the client folder (e.g. Interface/Cursor.ozt — varies by season/client);
2. Make a backup: copy Interface\Cursor.ozt Interface\Cursor.ozt.bak;
3. Convert the .ozt to .png in the MU converter, preserving the alpha channel;
4. Open the .png in the editor and note the exact dimensions (e.g. 32x32 or 64x64 — varies);
5. Draw your new pointer keeping:

• The same image size;
• The "hotspot" (the tip that actually clicks) in the same place as the original, usually the top-left corner;
• Transparency around the pointer (don't flatten it onto a solid background);

1. Export as .png with alpha preserved;
2. Convert back to .ozt;
3. Replace the texture in the client and test by moving the mouse across the game screen.

Watch out for the "hotspot"

The hotspot is the exact cursor pixel that counts as the click. If your art shifts the tip of the pointer to the center of the image, the player will click "off" — they aim at a monster and hit the ground beside it. To avoid this:

1. Open the original cursor and identify where the active tip is;
2. When redrawing, keep the new cursor's tip on the same pixel;
3. If your client's engine allows configuring the hotspot in an external file, adjust it there; otherwise, align the art to the original's fixed hotspot.

Swap the Main.exe icon

The icon that shows up in the taskbar, in Alt+Tab and in Explorer is a resource embedded in the executable. To swap it you first need a well-built .ico.

Generate a multi-size .ico

A good .ico contains several resolutions in the same image (16x16, 32x32, 48x48, 256x256) so Windows can pick the right one in each context.

# Generate a multi-size .ico with ImageMagick (PowerShell)
magick convert logo.png -resize 256x256 icon_256.png
magick convert logo.png -resize 48x48  icon_48.png
magick convert logo.png -resize 32x32  icon_32.png
magick convert logo.png -resize 16x16  icon_16.png
magick convert icon_256.png icon_48.png icon_32.png icon_16.png servidor-mu.ico

If you prefer a no-command-line route, IcoFX and various online converters generate a multi-size .ico from a PNG.

Replace the icon with Resource Hacker

1. Open Resource Hacker;
2. File → Open → select Main.exe;
3. In the left pane, expand Icon Group;
4. Right-click the existing icon group → Replace Icon (or Replace Resource);
5. Select your servidor-mu.ico;
6. File → Save (Resource Hacker creates an _original safety copy in some cases, but keep your own backup anyway);
7. Close and check the new icon in Explorer.

When the icon "won't change"

Windows keeps an aggressive icon cache. If you swapped the icon and Explorer still shows the old one:

1. Run in the terminal: ie4uinit.exe -show;
2. If that doesn't fix it, restart the Explorer process (Task Manager → Windows Explorer → Restart);
3. Confirm the shortcut points to the edited Main.exe, and not to an old copy in another folder;
4. As a last resort, clear the icon cache and log off/on.

Swap in-game UI icons

Shop buttons, events, hotkeys and the minimap are also textures. The process is identical to the cursor's:

1. Batch-convert the .ozj/.ozt files in Interface/ to view them as thumbnails;
2. Identify the icon you want to swap;
3. Edit it keeping the dimensions and transparency;
4. Reconvert and replace;
5. Test in game by opening the corresponding window/system.

Reference formats and dimensions

Example values — they vary by season/client, always check the original file:

Common errors and fixes

Package and distribute

# Package only the changed files (PowerShell + 7-Zip)
& "C:\Program Files\7-Zip\7z.exe" a -t7z -mx=9 patch-visual.7z Interface\ Main.exe

# Integrity hash to publish on the site
Get-FileHash patch-visual.7z -Algorithm SHA256 | Select-Object Hash

If you use a launcher/updater, add the modified files to the update list so players automatically receive the new cursor and icons.

Launch checklist

• Backup of the texture folder and Main.exe in _original/
• Real cursor file name and format confirmed in your client
• Cursor recreated at the exact dimensions, with transparency
• Hotspot (active tip) aligned to the original — click tested in game
• .ico generated with multiple sizes (16/32/48/256)
• Main.exe icon replaced via Resource Hacker
• Windows icon cache refreshed and icon confirmed
• In-game UI icons standardized in the same style
• Client opened from the shortcut to the game without crashes
• Patch compressed and SHA256 hash published
• Files added to the launcher/updater list (if any)

Frequently asked questions