Mega Files (extension: .MEG) in Petroglyph's games are used to store the collection of game files. By packing these files into a single large file, the operating-system overhead of storing and opening each individual file is removed and it helps avoid fragmentation.

Each Mega File begins with a header, followed by the Filename Table, the File Table and finally, the file data.

Header:
  +0000h  numFilenames  uint32   ; Number of filenames in the Filename Table
  +0004h  numFiles      uint32   ; Number of files in the File Table

Filename Table record:
  +0000h  length        uint16   ; Length of the filename, in characters
  +0004h  name          length   ; The ASCII filename

File Table record:
  +0000h  crc           uint32   ; CRC-32 of the filename
  +0004h  index         uint32   ; Index of this record in the table
  +0008h  size          uint32   ; Size of the file, in bytes
  +000Ch  start         uint32   ; Start of the file, in bytes 
  +0010h  name          uint32   ; Index in the Filename Table of the filename

Notes:

• The number of files and number of filenames are always equal (so far).
• The filenames are NOT zero-terminated.
• The start offset is from the beginning of the Mega File.
• The File Table is sorted on the CRC.

It is common or just possible for Petroglyph's games to have multiple Mega Files, and even Mega Files for user mods. All used Mega Files are listed in MegaFiles.xml in a game directory. Petroglyph's games read this file and, load all Mega Files and merge their File Table to create one Master File Table. If a file occurs in multiple Mega Files, the file in the Mega File listed last in MegaFiles.xml will be used.