Monsters can't melee attack player, while player "stands" on them. It is a bit hard to repead this trick with other monsters than Demon, but this seems to be actual for all monsters who have melee attack.
Here's how it looks: https://youtu.be/b435AG4z-qM
Suggestion: Add somekind of vertical checking to "ATTACKRANGE=" in ATTACKS.DDF...?
Some more discovered info: setting much higher "ATTACKRANGE" in ATTACKS.DDF does not change situation.For example, I have tried to set Demon's range to 640 - now he can attack from long distance, but still not while I'm on top of him. So this seems to be not radius+height+attack distance mess.
This simple map will help with chicking, all close attack type monsters are placed in "pits", don't need to play rodeo in game :) https://1drv.ms/u/s!Akj1GftRhTs2grpRj_NQ_Ti7c733Fg
Fixed and added to the Git repo -- will be in Test3! =D