No monsters mode

No monsters mode is a mode that excludes monsters when playing Doom, Doom II, Final Doom and other Doom-based games. It is implemented by the "-nomonsters" command on the command line.

Bugs
Several bugs are present with no monsters mode. On some levels, monsters are a necessity for exiting the level. Also, the icon of sin's monster spawner is ignored by the -nomonsters command line argument.