Is there a way for enemies who cannot damage each other to...damage each other?

As the subject states, I'm curious if anyone out there has made a mod or whatever that does this? Like Barons cannot harm barons, Imps can't harm imps and etc. etc. I know they are "hard coded" not to harm each other (except for the occasional barrel explosion, blahblahblah). Was just wondering, 'tis all.

Projectiles are hardcoded to not harm monsters of the same type as the monster who fired the projectile. But other types of attack (hitscan, melee, radius explosion, charge ala Lost Soul) can deal damage to monsters of the same type. Melee attacks themselves cannot provoke infighting between monsters who aren't infighting yet, though - so that monsters of the same type who only have melee attack, or only melee + projectile attack, or only projectile attack, cannot normally get into infighting each other. However, barrels can be used to provoke infighting even between monsters of the same type - so that monster types with melee attack or melee + projectile attack can harm each other through the melee attack. Monsters with merely projectile attack will never actually harm each other even during infighting each other, though.

EDIT: Making projectiles actually harm monsters of the same type as who fired them is as easy as setting one flag in DEHACKED, which will affect all projectiles in the whole wad, though, it cannot be used only to affect specific projectiles.

I once tried to discover convoluted ways to get other enemies to target Pain Elementals and Archviles.

The Pain Elemental has "clean hands"?

PEs were an interesting case because while they are not explicitly protected from retaliation like Archiviles, there's no plausible/legal way for a monster to attack them in retaliation for infighting. The PE itself of course can get mad at other monsters and attack them, but the trick is that, as far as the game code is concerned, it's not itself responsible for its attacks: the Lost Souls it spits out are ;-)

What kind of game will look like with that mod? Thuh...
I'm not big programmer but maybe if in projectile code put random script which will change number which checks in code when projectile touched someone... ppfff
something like this:
For example Imp's ball has 5001 number and Imp itself has the same. So if Imp's ball attacked someone - code will check that number and if it the same then ignore, if not - get.
I mean put some random factor in that number to create instead 5001 more variations. Is it possible in Doom code?

FWIW there are some ZDaemon Survival servers which use some kind of "infighting for all" mod and...well....TBQH it only makes a difference in maps where this would be immediately noticeable, e.g. large crowds of Revenants or HKs, but also multiple Cyberdemons firing at each other. Nothing worth holding your breath about.

Azuruish said:

I'm not big programmer but maybe if in projectile code put random script which will change number which checks in code when projectile touched someone... ppfff
something like this:
For example Imp's ball has 5001 number and Imp itself has the same. So if Imp's ball attacked someone - code will check that number and if it the same then ignore, if not - get.
I mean put some random factor in that number to create instead 5001 more variations. Is it possible in Doom code?

What?

I'm confused what's even the purpose you wanted to achieve now? I already said that making a DEHACKED mod to make projectiles harm monsters of the same type is easy.

He probably meant if monsters of the same species could infight occasionally/randomly. Well, not with DEHACKED alone, though with some The Sky May Be type of hacking, even that could be done (remember those monsters turning into others?)