ZDoom

Yes. And inversely you could put COUNTKILL on things that aren't monsters, such as barrels.

[quote="Ghastly"][quote="Nevander"]But won't that up the monster count by 1 for every MapSpot and result in a ton of unkillable monsters? Or is ZDoom smart enough to see it's not an actual monster?[/quote]
It's only counted if it has the +CountKill flag, which +IsMonster doesn't add automatically. If you want to make absolutely sure, throw -CountKill on it, but that's not necessary.[/quote]
Ahh I see. I knew about +COUNTITEM and +COUNTSECRET but not +COUNTKILL. I guess I always assumed that if something is a monster then it will always count as one. Does that mean you could define a new monster actor and do -COUNTKILL on it and it wouldn't count? Like make little worm enemies that attack you but aren't counted as an actual monster... kinda like how Blood had the rats that would attack you.

[quote="Nevander"]But won't that up the monster count by 1 for every MapSpot and result in a ton of unkillable monsters? Or is ZDoom smart enough to see it's not an actual monster?[/quote]
It's only counted if it has the +CountKill flag, which +IsMonster doesn't add automatically. If you want to make absolutely sure, throw -CountKill on it, but that's not necessary.

[quote="ZzZombo"]You can create your own subclass of MapSpot and give it +ISMONSTER flag. Bam, it's affected by the setting.[/quote]
RIP me. Never even thought of doing that...

EDIT: But won't that up the monster count by 1 for every MapSpot and result in a ton of unkillable monsters? Or is ZDoom smart enough to see it's not an actual monster?

You can create your own subclass of MapSpot and give it +ISMONSTER flag. Bam, it's affected by the setting.

If it would be possible, it would come in handy to be able to allow or disallow other things besides monsters in no monsters mode. You might wonder when this would come in handy, well, [wiki]SpawnSpot[/wiki] is a good example. The wiki page states:

[quote]Note that this function does not make teleport fog appear when the actor(s) spawn. Since the teleport effect is simply another actor, you can manually do this by spawning a TeleportFog actor at the same time.[/quote]

This of course means that since a MapSpot thing is NOT a monster, it WILL spawn in no monsters mode and thus will also cause the TeleportFog actor to spawn when called upon by the script. If it were possible to tick off a flag checkbox to disallow the thing to spawn even in no monsters mode, this issue would be resolved since the MapSpot would not be present to spawn the fog at. Just like if you deselect a MapSpot to be on a specific skill setting, that MapSpot will not exist on the map when played on that skill and thus isn't involved with a script which would otherwise use it.