About

RGZ is used by the Ragnarok Online(tm) patcher to distribute new files, like executables, music, etc.

Ragnarok Online is a registered trademark of Gravity Co., Ltd.
This site is in no way affiliated with them.

Format:

A rgz file is similar to a tar.gz file, but uses a very simple format instead of tar.

Entry header

Present for the end entry and every file/directory.

 name           | size
----------------+----------------------
 type           | 1 byte
 filenameLength | 1 byte
 filename       | filenameLength bytes

type - type of entry
'd' - directory
'f' - file
'e' - end entry

filenameLength - length of filename

filename - nul-terminated filename

File data

Present after each file header.

 name   | size
--------+--------------
 length | 4 bytes
 data   | length bytes

length - length of data

data - file data

End entry

There must always be an end entry.
Everything after the end entry is discarded.
The filename in the header should contain "end".