.W3M File Extension
File TypeWarcraft 3 Map File
This file is saved in a binary format, which requires a specific program to read its contents.
What is a W3M file?
Game map used by Warcraft III: Reign of Chaos; includes terrain, objects, and resources placed within the map; may be included with the game or created by players with the Warcraft III World Editor.
NOTE: Maps for the Warcraft III expansion pack use the .W3X extension.