A GUI launcher or frontend allows the user to start Doom by using a graphical interface as opposed to the command line. Most of the common commands used for setting up the game can be accessed by a launcher, such as the skill level and the map to start on.
Various launchers for Doom-engine games exist. Some are included as part of precompiled source ports, while others must be installed separately. Most notably, Doom95 has a GUI launcher (which can be deactivated with the -nodm command line argument).