No monsters mode
On the Doom Speed Demo Archive it is also a speedrunning category named NoMo that requires completing a level as fast as possible without monsters, while NoMo 100S additionally requires collecting all secrets.
Several bugs are present with no monsters mode. On some levels, such as in the boss maps of Doom and in MAP32: Grosse of Doom II, monsters are a necessity for exiting. Also, the Icon of Sin's monster spawner is ignored by the -nomonsters parameter. When a level with a lone spawner and Romero's head is completed, each kill aside from the head adds 100% to the kill percentage.