Adds "Teach them a lesson" Objective (traitor only) (#22933)

* Adds the tech them a lesson objective.

* minor changes

* SPACING!

* onesmallupdate

* requestedchanges

* requestedchanges

code/datums/mind.dm

@@ -631,7 +631,7 @@
 				def_value = "custom"
 
 		var/new_obj_type = input("Select objective type:", "Objective type", def_value) as null|anything in	list(
-			"assassinate", "blood", "debrain", "protect", "prevent", "hijack", "escape", "survive", "steal", "download",
+			"assassinate", "assassinateonce", "blood", "debrain", "protect", "prevent", "hijack", "escape", "survive", "steal", "download",
 			"nuclear", "capture", "absorb", "destroy", "maroon", "identity theft", "custom")
 		if(!new_obj_type)
 			return
@@ -639,7 +639,7 @@
 		var/datum/objective/new_objective = null
 
 		switch(new_obj_type)
-			if("assassinate","protect","debrain", "maroon")
+			if("assassinate", "assassinateonce", "protect","debrain", "maroon")
 				//To determine what to name the objective in explanation text.
 				var/objective_type_capital = uppertext(copytext(new_obj_type, 1,2))//Capitalize first letter.
 				var/objective_type_text = copytext(new_obj_type, 2)//Leave the rest of the text.
@@ -654,7 +654,7 @@
 							possible_targets_random += possible_target.current // For random picking, only valid targets
 
 				var/mob/def_target = null
-				var/objective_list[] = list(/datum/objective/assassinate, /datum/objective/protect, /datum/objective/debrain)
+				var/objective_list[] = list(/datum/objective/assassinate, /datum/objective/assassinateonce, /datum/objective/protect, /datum/objective/debrain)
 				if(objective&&(objective.type in objective_list) && objective:target)
 					def_target = objective.target.current
 				possible_targets = sortAtom(possible_targets)

code/game/gamemodes/objective.dm

@@ -107,6 +107,7 @@ GLOBAL_LIST_INIT(potential_theft_objectives, (subtypesof(/datum/theft_objective)
 
 		possible_targets += possible_target
 
+
 	if(possible_targets.len > 0)
 		target = pick(possible_targets)
 
@@ -164,6 +165,32 @@ GLOBAL_LIST_INIT(potential_theft_objectives, (subtypesof(/datum/theft_objective)
 		return FALSE
 	return TRUE
 
+/datum/objective/assassinateonce
+	name = "Assassinate once"
+	martyr_compatible = TRUE
+	var/won = FALSE
+
+/datum/objective/assassinateonce/find_target(list/target_blacklist)
+	..()
+	if(target?.current)
+		explanation_text = "Teach [target.current.real_name], the [target.assigned_role], a lesson they will not forget. The target only needs to die once for success."
+		RegisterSignal(target.current, list(COMSIG_MOB_DEATH, COMSIG_PARENT_QDELETING), PROC_REF(check_midround_completion))
+	else
+		explanation_text = "Free Objective"
+	return target
+
+/datum/objective/assassinateonce/check_completion()
+	return won || completed || !target?.current?.ckey
+
+/datum/objective/assassinateonce/proc/check_midround_completion()
+	won = TRUE
+	UnregisterSignal(target.current, list(COMSIG_MOB_DEATH, COMSIG_PARENT_QDELETING))
+
+/datum/objective/assassinateonce/on_target_cryo()
+	if(won)
+		return
+	return ..()
+
 
 /datum/objective/mutiny
 	name = "Mutiny"

code/modules/antagonists/traitor/datum_traitor.dm

@@ -130,6 +130,8 @@
 			add_antag_objective(/datum/objective/debrain)
 		else if(prob(30))
 			add_antag_objective(/datum/objective/maroon)
+		else if(prob(30))
+			add_antag_objective(/datum/objective/assassinateonce)
 		else
 			add_antag_objective(/datum/objective/assassinate)
 	else