A file with .w3n extension is a campaign maps file used by Warcraft III: The Frozen Throne game which is an extension of the Warcraft III, an all time famous video game. The W3N file contains campaign maps that is used to create custom campaigns using the series of missions data available in it. The format is oftenly misunderstood as map files and users don’t get an idea why their W3N files are not getting loaded in Frozen Throne. W3N files can be opened with Blizzard Warcraft 3: The Frozen Throne.
W3N File Format - More Information
W3N files are stored to disc as binary files and their internal file format is not available publicly. The Campaign Editor component of the Warcraft III World Editor though allows to create W3N files.
How to Install W3N files?
Don’t be mistaken by placing the W3N files in the “maps” folder on your computer. W3N files are not map files, but campaigns that can be used to created missions. Therefore, to load these files, these should be placed in the “campaigns” folder and not the “maps” folder.