Allows mobs with no usable legs to walk if holding two canes

code/__DEFINES/dcs/signals/signals_mob/signals_mob_carbon.dm

@@ -151,3 +151,7 @@
 
 /// Sent at the very end of human character setup
 #define COMSIG_HUMAN_CHARACTER_SETUP "after_human_setup"
+
+/// from /datum/status_effect/limp/proc/check_step()
+#define COMSIG_CARBON_LIMPING "mob_limp_check"
+	#define COMPONENT_CANCEL_LIMP (1<<0)

code/__DEFINES/living.dm

@@ -66,6 +66,11 @@
 /// The trait that determines if someone has the robotic limb reattachment quirk.
 #define TRAIT_ROBOTIC_LIMBATTACHMENT "trait_robotic_limbattachment"
 
+/// Mob can walk despite having two disabled/missing legs so long as they have two of this trait.
+/// Kind of jank, refactor at a later day when I can think of a better solution.
+/// Just be sure to call update_limbless_locomotion() after applying / removal
+#define TRAIT_NO_LEG_AID "no_leg_aid"
+
 #define COLOR_BLOOD "#c90000"
 
 // Used in ready menu anominity

code/datums/status_effects/wound_effects.dm

@@ -70,6 +70,9 @@
 	if(!owner.client || owner.body_position == LYING_DOWN || !owner.has_gravity() || (owner.movement_type & (FLYING|FLOATING)) || forced || owner.buckled)
 		return
 
+	if(SEND_SIGNAL(owner, COMSIG_CARBON_LIMPING, (next_leg || right || left)) & COMPONENT_CANCEL_LIMP)
+		return
+
 	// less limping while we have determination still
 	var/determined_mod = owner.has_status_effect(/datum/status_effect/determined) ? 0.5 : 1
 

code/game/objects/items/weaponry.dm

@@ -519,6 +519,28 @@ for further reading, please see: https://github.com/tgstation/tgstation/pull/301
 	playsound(src, 'sound/weapons/batonextend.ogg', 50, TRUE)
 	return COMPONENT_NO_DEFAULT_MESSAGE
 
+/obj/item/cane/crutch
+	name = "medical crutch"
+	desc = "A medical crutch used by people missing a leg. Not all that useful if you're missing both of them, though."
+	icon = 'icons/obj/weapons/staff.dmi'
+	icon_state = "crutch_med"
+	inhand_icon_state = "crutch_med"
+	lefthand_file = 'icons/mob/inhands/weapons/melee_lefthand.dmi'
+	righthand_file = 'icons/mob/inhands/weapons/melee_righthand.dmi'
+	force = 12
+	throwforce = 8
+	w_class = WEIGHT_CLASS_BULKY
+	custom_materials = list(/datum/material/iron = SMALL_MATERIAL_AMOUNT * 0.5)
+	attack_verb_continuous = list("bludgeons", "whacks", "thrashes")
+	attack_verb_simple = list("bludgeon", "whack", "thrash")
+
+/obj/item/cane/crutch/wood
+	name = "wooden crutch"
+	desc = "A handmade crutch. Also makes a decent bludgeon if you need it."
+	icon_state = "crutch_wood"
+	inhand_icon_state = "crutch_wood"
+	custom_materials = list(/datum/material/wood = SMALL_MATERIAL_AMOUNT * 0.5)
+
 /obj/item/staff
 	name = "wizard staff"
 	desc = "Apparently a staff used by the wizard."

code/modules/mob/living/carbon/carbon_movement.dm

@@ -33,52 +33,25 @@
 			has_momentum = FALSE
 	// NON-MODULE CHANGE END
 
-/mob/living/carbon/set_usable_legs(new_value)
-	. = ..()
-	if(isnull(.))
-		return
-	if(. == 0)
-		if(usable_legs != 0) //From having no usable legs to having some.
-			REMOVE_TRAIT(src, TRAIT_FLOORED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-			REMOVE_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-	else if(usable_legs == 0 && !(movement_type & (FLYING | FLOATING))) //From having usable legs to no longer having them.
-		ADD_TRAIT(src, TRAIT_FLOORED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-		if(!usable_hands)
-			ADD_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-
-
+// NON-MODULE CHANGE START
 /mob/living/carbon/set_usable_hands(new_value)
 	. = ..()
 	if(isnull(.))
 		return
 	if(. == 0)
 		REMOVE_TRAIT(src, TRAIT_HANDS_BLOCKED, LACKING_MANIPULATION_APPENDAGES_TRAIT)
-		if(usable_hands != 0) //From having no usable hands to having some.
-			REMOVE_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
 	else if(usable_hands == 0 && default_num_hands > 0) //From having usable hands to no longer having them.
 		ADD_TRAIT(src, TRAIT_HANDS_BLOCKED, LACKING_MANIPULATION_APPENDAGES_TRAIT)
-		if(!usable_legs && !(movement_type & (FLYING | FLOATING)))
-			ADD_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
 
 /mob/living/carbon/on_movement_type_flag_enabled(datum/source, flag, old_movement_type)
 	. = ..()
 	if(movement_type & (FLYING | FLOATING) && !(old_movement_type & (FLYING | FLOATING)))
-		remove_movespeed_modifier(/datum/movespeed_modifier/limbless)
-		remove_traits(list(TRAIT_FLOORED, TRAIT_IMMOBILIZED), LACKING_LOCOMOTION_APPENDAGES_TRAIT)
+		update_limbless_locomotion()
+		update_limbless_movespeed_mod()
 
 /mob/living/carbon/on_movement_type_flag_disabled(datum/source, flag, old_movement_type)
 	. = ..()
 	if(old_movement_type & (FLYING | FLOATING) && !(movement_type & (FLYING | FLOATING)))
-		var/limbless_slowdown = 0
-		if(usable_legs < default_num_legs)
-			limbless_slowdown += (default_num_legs - usable_legs) * 3
-			if(!usable_legs)
-				ADD_TRAIT(src, TRAIT_FLOORED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-				if(usable_hands < default_num_hands)
-					limbless_slowdown += (default_num_hands - usable_hands) * 3
-					if(!usable_hands)
-						ADD_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-		if(limbless_slowdown)
-			add_or_update_variable_movespeed_modifier(/datum/movespeed_modifier/limbless, multiplicative_slowdown = limbless_slowdown)
-		else
-			remove_movespeed_modifier(/datum/movespeed_modifier/limbless)
+		update_limbless_locomotion()
+		update_limbless_movespeed_mod()
+// NON-MODULE CHANGE END

code/modules/mob/living/carbon/human/examine.dm

@@ -166,7 +166,7 @@
 			damage_text = "limp and lifeless"
 		else
 			damage_text = (body_part.brute_dam >= body_part.burn_dam) ? body_part.heavy_brute_msg : body_part.heavy_burn_msg
-		msg += "<B>[capitalize(t_his)] [body_part.name] is [damage_text]!</B>\n"
+		msg += "<B>[capitalize(t_his)] [body_part.plaintext_zone] is [damage_text]!</B>\n"
 
 	//stores missing limbs
 	var/l_limbs_missing = 0

code/modules/mob/living/living.dm

@@ -2269,6 +2269,7 @@ GLOBAL_LIST_EMPTY(fire_appearances)
 	num_legs = new_value
 
 
+// NON-MODULE CHANGE START
 ///Proc to modify the value of usable_legs and hook behavior associated to this event.
 /mob/living/proc/set_usable_legs(new_value)
 	if(usable_legs == new_value)
@@ -2277,19 +2278,23 @@ GLOBAL_LIST_EMPTY(fire_appearances)
 		stack_trace("[src] had set_usable_legs() called on them with a negative value!")
 		new_value = 0
 
-	. = usable_legs
+	var/old_value = usable_legs
 	usable_legs = new_value
 
-	if(new_value > .) // Gained leg usage.
+	update_limbless_locomotion()
+	update_limbless_movespeed_mod()
+
+	return old_value
+
+/// Updates whether the mob is floored or immobilized based on how many limbs they have or are missing.
+/mob/living/proc/update_limbless_locomotion()
+	if(usable_legs > 0 || (movement_type & (FLYING|FLOATING)) || COUNT_TRAIT_SOURCES(src, TRAIT_NO_LEG_AID) >= 2)
 		REMOVE_TRAIT(src, TRAIT_FLOORED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
 		REMOVE_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-	else if(!(movement_type & (FLYING | FLOATING))) //Lost leg usage, not flying.
-		if(!usable_legs)
-			ADD_TRAIT(src, TRAIT_FLOORED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-			if(!usable_hands)
-				ADD_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-
-	update_limbless_movespeed_mod()
+		return
+	ADD_TRAIT(src, TRAIT_FLOORED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
+	if(usable_hands == 0)
+		ADD_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
 
 /// Updates the mob's movespeed based on how many limbs they have or are missing.
 /mob/living/proc/update_limbless_movespeed_mod()
@@ -2305,6 +2310,7 @@ GLOBAL_LIST_EMPTY(fire_appearances)
 		add_or_update_variable_movespeed_modifier(/datum/movespeed_modifier/limbless, multiplicative_slowdown = limbless_slowdown)
 	else
 		remove_movespeed_modifier(/datum/movespeed_modifier/limbless)
+// NON-MODULE CHANGE END
 
 ///Proc to modify the value of num_hands and hook behavior associated to this event.
 /mob/living/proc/set_num_hands(new_value)
@@ -2314,18 +2320,24 @@ GLOBAL_LIST_EMPTY(fire_appearances)
 	num_hands = new_value
 
 
+// NON-MODULE CHANGE START
 ///Proc to modify the value of usable_hands and hook behavior associated to this event.
 /mob/living/proc/set_usable_hands(new_value)
 	if(usable_hands == new_value)
 		return
-	. = usable_hands
+	if(new_value < 0) // Sanity check
+		stack_trace("[src] had set_usable_hands() called on them with a negative value!")
+		new_value = 0
+
+	var/old_value = usable_hands
 	usable_hands = new_value
 
-	if(new_value > .) // Gained hand usage.
-		REMOVE_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
-	else if(!(movement_type & (FLYING | FLOATING)) && !usable_hands && !usable_legs) //Lost a hand, not flying, no hands left, no legs.
-		ADD_TRAIT(src, TRAIT_IMMOBILIZED, LACKING_LOCOMOTION_APPENDAGES_TRAIT)
+	if(usable_legs < default_num_legs)
+		update_limbless_locomotion()
+		update_limbless_movespeed_mod()
 
+	return old_value
+// NON-MODULE CHANGE END
 
 /// Whether or not this mob will escape from storages while being picked up/held.
 /mob/living/proc/will_escape_storage()

maplestation_modules/code/datums/components/limbless_aid.dm

@@ -26,26 +26,53 @@
 
 	var/obj/item/item_parent = parent
 	if(isliving(item_parent.loc))
-		var/mob/living/wearer = item_parent.loc
-		UnregisterSignal(wearer, COMSIG_LIVING_LIMBLESS_MOVESPEED_UPDATE)
-		wearer.update_limbless_movespeed_mod()
+		on_drop(item_parent, item_parent.loc)
 
 /datum/component/limbless_aid/proc/on_equip(obj/item/source, mob/living/user, slot)
 	SIGNAL_HANDLER
 
 	if(!(slot & required_slot))
 		return
 
+	ADD_TRAIT(user, TRAIT_NO_LEG_AID, REF(src))
 	RegisterSignal(user, COMSIG_LIVING_LIMBLESS_MOVESPEED_UPDATE, PROC_REF(modify_movespeed), override = TRUE)
+	RegisterSignal(user, COMSIG_CARBON_LIMPING, PROC_REF(limp_check), override = TRUE)
+	user.update_limbless_locomotion()
 	user.update_limbless_movespeed_mod()
 
 /datum/component/limbless_aid/proc/on_drop(obj/item/source, mob/living/user)
 	SIGNAL_HANDLER
 
+	REMOVE_TRAIT(user, TRAIT_NO_LEG_AID, REF(src))
 	UnregisterSignal(user, COMSIG_LIVING_LIMBLESS_MOVESPEED_UPDATE)
+	UnregisterSignal(user, COMSIG_CARBON_LIMPING)
+	user.update_limbless_locomotion()
 	user.update_limbless_movespeed_mod()
 
 /datum/component/limbless_aid/proc/modify_movespeed(mob/living/source, list/modifiers)
 	SIGNAL_HANDLER
 
-	modifiers += movespeed_mod
+	var/obj/item/bodypart/leg = get_braced_leg(source)
+	if(isnull(leg) || leg.bodypart_disabled)
+		modifiers += movespeed_mod
+
+/datum/component/limbless_aid/proc/limp_check(mob/living/source, obj/item/bodypart/next_leg)
+	SIGNAL_HANDLER
+
+	var/obj/item/bodypart/leg = get_braced_leg(source)
+	if(isnull(leg) || leg == next_leg)
+		return COMPONENT_CANCEL_LIMP
+
+#define IS_RIGHT_ARM(index) (index % 2 == 0)
+
+/// Checks what side the item is equipped on
+/datum/component/limbless_aid/proc/get_braced_leg(mob/living/who)
+	if(required_slot & ITEM_SLOT_HANDS)
+		// note this is backwards intentionally:
+		// right arm braces the left leg, and left arm braces right leg
+		var/side = IS_RIGHT_ARM(who.get_held_index_of_item(parent)) ? BODY_ZONE_L_LEG : BODY_ZONE_R_LEG
+		return who.get_bodypart(side)
+
+	return null // unimplemented
+
+#undef IS_RIGHT_ARM