What is a map file and how do I open a map file?
The MAP extension is given to an uncompiled game map file. These MAP files were developed by id software and are saved in a text format that humans can read. MAP files can either be a binary map file compilation used for Half Life and Quake games. MAP files are built with a number of map editors, including Valve Hammer Editor. Torque Constructor uses MAP files to transform maps into the DIF format for development for Torque games. These files can also be used for Torque games, targeting several platforms such as PC, mobile and console. MAP formats are utilized by numerous game engines like the Quake engines, Goldsource Engine, Unreal Engine, Dark Engine and Torque Engine. MAP files can be stored as newer VMF formats with the use of Valve Hammer Editor 4, a program previously called "Worldcraft”.Many game engines use the MAP format.
Relevant map file links:How to open map file on Youtube
How to open map file on Wikipedia
How to open map file on Microsoft.com