IWADs are complete sets of game data (such as DOOM2.WAD).
Where can I get DOOM2.WAD or other official IWADs?
From the original game retail diskettes, CDs and electronic download retail products (from Steam or id Software online store).
Shareware versions of these games can be acquired from http://www.idsoftware.com/.
Where to put WAD files so that Doomsday can find them?
- You can use the -iwad command line option to tell Doomsday where you have your IWADs.
- All platforms: The environment variables DOOMWADDIR and DOOMWADPATH determine where Doomsday looks IWAD files.
- Unix (including macOS): You can specify the IWAD folder in your paths configuration file.