How to edit the fonts and text of the MU Online client

Few changes convey as much identity to a MU Online server as typography and text. The font used in character names, the style of the system messages, the interface language and even small welcome phrases shape the first impression of anyone who logs in. This intermediate-level tutorial shows how to change the client's font, adjust size and color, and safely edit the text strings — from those in external files to those embedded in Main.exe — without breaking the game in the process.

Everything here happens on the client side: the server sends codes and values, and it's each player's client that turns that into text on screen. That's why any change has to be distributed together with the client. If you don't yet have that client set up and pointing to your server, it's worth starting with the guide on how to create a MU Online server and coming back here with the foundation ready.

Prerequisites

• A MU client compatible with the server's season, working.
• An advanced text editor — Notepad++ or VS Code, with explicit control over encoding. It's indispensable.
• A hex editor — HxD, only if you're going to edit strings inside Main.exe.
• One or more fonts installed on Windows that you intend to use, with support for the necessary characters.
• A full backup of the client, especially Main.exe and the text folder, before any editing.

Where text lives in the MU client

MU's text is spread across three distinct layers, and knowing which one to edit is half the work:

1. External text files — system messages, interface text, notices and, in many seasons, the language files. They typically live in Data/Local/. These are the easiest and safest to edit.
2. Data files — item, monster and map names. They usually come from their own files (for example item lists), sometimes in text, sometimes in the client's binary format.
3. Strings embedded in Main.exe — some fixed messages, titles and low-level text are inside the executable. Editing them requires a hex editor and attention to length.

Map of text types

Typical text-file structure

Bearing in mind that the names and organization vary by season/client:

MUClient/
├── Data/
│   └── Local/
│       ├── eng/                 ← English text
│       │   ├── Message.txt      ← system/error messages
│       │   ├── ItemName.txt     ← item names
│       │   └── MonsterName.txt  ← monster names
│       └── por/                 ← custom language folder (e.g. Portuguese)
├── Main.exe                     ← fixed embedded strings
└── Main.ini / Font.ini          ← font configuration (varies)

Step 1 — Change the client font

The main MU font is usually defined by a system font name, read from a configuration file or embedded in the executable. The safest path is the configuration file, when it exists:

1. Locate the font configuration file (something like Font.ini, or a section in Main.ini — varies by season/client).
2. Open it in Notepad++ and find the key that names the font, for example FontName.
3. Replace it with the exact name of a font installed on Windows (the name must match the one registered in the system, not the name of the .ttf file).
4. Adjust, if available, the size and weight (bold) fields.
5. Save and test in the game.

; Font.ini  (ILLUSTRATIVE — fields and existence vary by season/client)
[Font]
FontName=Tahoma
FontSize=14
Bold=0
Antialias=1

Distributing a custom font

If you opt for your own font:

1. Include the .ttf file in the client folder.
2. In the launcher/installer, copy the font to the Windows fonts folder or register it temporarily.
3. Test on a clean machine (without the font pre-installed) to make sure the distribution works.

Step 2 — Adjust text size and color

The size usually comes from the same font file. Color, on the other hand, is generally tied to the type of message (normal chat, whisper, system, guild) and is defined internally:

• Global size: adjust FontSize with care — very large fonts overflow fixed-width interface text boxes.
• Colors per chat channel: in some seasons there's a configurable mapping; in others, the colors are embedded. Confirm which is your case before promising a specific palette.

Step 3 — Edit messages and interface text

Here's the most visible gain: translating and customizing the messages. The process:

1. Identify the file (e.g. Message.txt) and find out its current encoding — in Notepad++, the encoding appears in the bottom bar.
2. Before editing, copy the file to the backup.
3. Edit keeping the structure of each line. Many files use an index/ID followed by the text, and changing the index breaks the mapping.
4. Preserve the formatting codes (color markers, breaks, or placeholders like %s and %d) exactly where they were.
5. Save in the same original encoding (don't convert to UTF-8 with BOM).

// Message.txt  (ILLUSTRATIVE — format varies by season/client)
// ID    Text
100      "Welcome to the server!"
101      "You received %d zen."
102      "Character %s connected."

Step 4 — Edit item and monster names

Item and monster names usually have their own files, often with a table structure:

1. Open the names file (e.g. ItemName.txt) in the editor.
2. Locate the line by the item's index/category.
3. Edit only the name field, without touching the numeric indices.
4. Respect the maximum length — very long names are cut off in the interface or, in fixed-width formats, corrupt the following records.
5. Save in the correct encoding.

Step 5 — Edit strings embedded in Main.exe

When the text is inside the executable, the process changes in nature. The critical rule: you can't increase the length of a string without reengineering, because that would shift bytes and break the binary.

1. Make a copy Main_original.exe.
2. Open Main.exe in HxD.
3. Use the text (string) search to locate the phrase you want to change.
4. Replace character by character, keeping the same number of bytes. If the new text is shorter, pad it with spaces; never let it be longer than the original.
5. Preserve the null byte (00) that terminates the string — don't overwrite it.
6. Save and test immediately.

Original (13 bytes):  W e l c o m e   t o   M U  00
Edited   (13 bytes):  W e l c o m e !   ␠ ␠ ␠  00

Step 6 — Resolve encoding (accents)

Since a good part of the audience is Brazilian, accents are inevitable. To get it right:

1. Find out the encoding your client expects (often a specific ANSI codepage — varies by season/client).
2. In Notepad++, use Encoding → Convert to only if you know the correct target codepage; otherwise, keep the original.
3. Test a phrase with all the accents (á, é, í, ó, ú, ã, õ, ç) in the game before translating everything.
4. If the accents turn into symbols, the problem is the save encoding, not the text.

Common errors and fixes

Launch checklist

• Backup of Main.exe and the text folders made
• Original encoding of each file identified and kept
• Font defined by exact system name (or .ttf distributed)
• FontSize tested on all the main screens
• System messages edited preserving indices and placeholders
• Item/monster names within the length limit
• Main.exe strings edited without changing the size in bytes
• Test phrase with all accents validated in the game
• No file accidentally saved as UTF-8 with BOM
• Client tested on a clean machine (without the font pre-installed)
• Client repackaged and verification hash updated

Editing fonts and text seems simple, but it's precisely where many servers stumble because of encoding and embedded strings. By following the discipline of always keeping the original encoding, preserving indices and placeholders, and never enlarging strings inside the executable, you can localize and customize all the client's text safely — delivering a cohesive experience, in good language and with your server's own character.

Frequently asked questions