If GZDoom is distributed without its game_support.pk3 file, it will be unable to detect the regular IWADs and limited to the custom IWAD in the same directory. This can be desirable for distributing stand-alone games without them automatically detecting games installed through GOG.com or Steam. This file also contains non-free assets derived from game data (such as fonts) which are unsuitable to commercial distribution, should you wish to sell a custom IWAD you have created. Such a commercial distribution should also omit brightmaps.pk3 and lights.pk3.
- provides a minimal base on which to build a functional game.