To play, an IWAD file is needed. This is a large file containing all of the
levels, graphics, sound effects, music and other material that make up the
game. IWAD files are named according to the game; the standard names are:
.TP
\fBdoom.wad, doom1.wad, doom2.wad, tnt.wad, plutonia.wad\fR
Doom, Doom II, Final Doom
.TP
\fBheretic.wad, heretic1.wad, hexen.wad, strife1.wad\fR
Heretic, Hexen and Strife (commercial Doom engine games).
.TP
\fBhacx.wad, chex.wad\fR
Hacx and Chex Quest - more obscure games based on the Doom engine.
.TP
\fBfreedm.wad, freedoom1.wad, freedoom2.wad\fR
The Freedoom open content IWAD files.
.LP
The following directory paths are searched in order to find an IWAD:
.TP
\fBCurrent working directory\fR
Any IWAD files found in the current working directory will be used in
preference to IWADs found in any other directories.
.TP
\fBDOOMWADDIR\fR
This environment variable can be set to contain a path to a single directory
in which to look for IWAD files. This environment variable is supported by
most Doom source ports.
.TP
\fBDOOMWADPATH\fR
This environment variable, if set, can contain a colon-separated list of
directories in which to look for IWAD files, or alternatively full paths to
specific IWAD files.
.TP
\fB$HOME/.local/share/games/doom\fR
Writeable directory in the user's home directory. The path can be overridden
using the \fBXDG_DATA_HOME\fR environment variable (see the XDG Base Directory
Specification).
.TP
\fB/usr/local/share/games/doom, /usr/share/games/doom\fR
System-wide locations that can be accessed by all users. The path
\fB/usr/share/games/doom\fR is a standard path that is supported by most
Doom source ports. These paths can be overridden using the \fBXDG_DATA_DIRS\fR
environment variable (see the XDG Base Directory Specification).
.LP
The above can be overridden on a one-time basis by using the \fB\-iwad\fR
command line parameter to provide the path to an IWAD file to use. This
parameter can also be used to specify the name of a particular IWAD to use
from one of the above paths. For example, '\fB-iwad doom.wad\fR' will search
the above paths for the file \fBdoom.wad\fR to use.