In a prior post, I described id's WAD format used by classic games such as DOOM and how to read them. This post covers how to write them. As with my first post, this only covers the original WAD format, not the enhanced ones which followed.
WAD "Where's All the Data" files used by DOOM and various other games are simple containers, similar to zip and other archive formats, without additional complexity (such as compression) and data-centric rather than file. This article describes how to read the WAD files used by DOOM, DOOM II, Rise of the Triad and similar games of that area. The article covers reading of a WAD and extracting its contents