Monsters fleeing

This bug is very limited, and can only be reproduced using level editors. It is possible to change the conduct of a monster so that it flees from the player instead of attacking them.

How to reproduce
Place three copies of the monster at the same location, facing North. Each only appears at one difficulty level. The Demon is recommended as the monster, as it cannot attack from a distance.

Place the player aligned with the monster, facing it from the South. If the player is too far to the left or right of the monster, the effect does not occur.

Final Effect
The final effect is that the monster flees from the player until it is stopped or until the player moves far enough to the left or right. It may be necessary to shoot the monster to trigger it.

Example
[[Media:MonsterFlee.WAD|MonsterFlee.WAD]] is a Doom II map which illustrates this bug. The player has to force the demon to open the door by shooting. Then, he has to get the blue skullkey to exit the level.