Games files (.wad) for Doom, Doom 2, etc.

To play the full games Doom, Doom2, Heretic, Hexen, etc. with GZ3Doom, you first need to obtain the .wad game data files for those games.

If you have one of those games installed, copy the .wad file from the install folder into your GZ3Doom folder. Or drag the .wad file onto the GZ3Doom executable.

Steam has doom engine games for sale:

Ultimate Doom (Doom 1):

http://store.steampowered.com/app/2280/

Doom 2:

http://store.steampowered.com/app/2300/

Package including Doom, Doom 2, Final Doom:

http://store.steampowered.com/sub/18397/

Heretic:

http://store.steampowered.com/app/2390/

Hexen:

http://store.steampowered.com/app/2360/

Shareware Doom (first episode of Doom 1)

http://www.doomworld.com/pageofdoom/shareware.html