WAD (Doom)
More info
- Creator
- id Software
- Released
- 1993
- Type
- Archive format
- Successor
- PAK file
The Doom engine's archive format — "Where's All the Data?" — and the reason the game had a mod scene before the word existed.
A WAD file is a flat collection of "lumps": named chunks of data with eight-character names, a directory, and a twelve-byte header starting with IWAD or PWAD. A level isn't one lump but a group — THINGS, LINEDEFS, SECTORS, NODES and others — where NODES holds the precomputed BSP tree.
The clever part was the PWAD: a "patch WAD" whose lumps override same-named ones in the game's IWAD. Players could swap levels, sounds and graphics without touching the executable. Editors such as DEU arrived in 1994, and id Software let it happen. The format is simple enough that new WADs still come out every week.