.PAK File Extension
File Type 1Video Game Package
Game archive used by video games such as Quake, Hexen, and Half-Life; may include graphics, objects, textures, sounds, and other game data "packed" into a single file; can be browsed or viewed with several applications.
NOTE: The format for a PAK file used by one game may differ from the PAK format used for a different game. Therefore, you may have to try multiple programs before opening your PAK file.
File Type 2PAK (Packed) File
Compressed archive format originating from DOS that can contain many files; data in a PAK file may be compressed or uncompressed, but is usually compressed using ZLIB compression.
File Type 3Simutrans Object File
File used by Simutrans, a free transportation simulation game; contains game object graphics and properties; compiled from a plain text ".dat" data file and a source .PNG image; used for game vehicles, buildings, terrain, and other objects.
To modify Simutrans objects, users typically don't edit the PAK files directly. Instead, they usually download the source DAT and PNG files used to package a PAK file, modify the files, and then re-pack the contents into a new PAK file. PAK files are built using the MakeObj.exe program.
NOTE: PakBuilder is a GUI program used to create PAK files. It cannot open them.