one way unrestricted airlocks!

code/game/machinery/doors/airlock.dm

@@ -621,6 +621,31 @@ About the new airlock wires panel:
 		if(user)
 			attack_ai(user)
 
+/obj/machinery/door/airlock/proc/check_unres() //unrestricted sides. This overlay indicates which directions the player can access even without an ID
+	if(hasPower() && unres_sides)
+		if(unres_sides & NORTH)
+			var/image/I = image(icon='icons/obj/doors/airlocks/station/overlays.dmi', icon_state="unres_n") //layer=src.layer+1
+			I.pixel_y = 32
+			set_light(l_range = 2, l_power = 1)
+			add_overlay(I)
+		if(unres_sides & SOUTH)
+			var/image/I = image(icon='icons/obj/doors/airlocks/station/overlays.dmi', icon_state="unres_s") //layer=src.layer+1
+			I.pixel_y = -32
+			set_light(l_range = 2, l_power = 1)
+			add_overlay(I)
+		if(unres_sides & EAST)
+			var/image/I = image(icon='icons/obj/doors/airlocks/station/overlays.dmi', icon_state="unres_e") //layer=src.layer+1
+			I.pixel_x = 32
+			set_light(l_range = 2, l_power = 1)
+			add_overlay(I)
+		if(unres_sides & WEST)
+			var/image/I = image(icon='icons/obj/doors/airlocks/station/overlays.dmi', icon_state="unres_w") //layer=src.layer+1
+			I.pixel_x = -32
+			set_light(l_range = 2, l_power = 1)
+			add_overlay(I)
+	else
+		set_light(0)
+		
 /obj/machinery/door/airlock/CanPass(atom/movable/mover, turf/target, height=0)
 	if(isElectrified() && density && istype(mover, /obj/item))
 		var/obj/item/I = mover

code/game/machinery/doors/door.dm

@@ -28,7 +28,7 @@
 	var/real_explosion_block	//ignore this, just use explosion_block
 	var/heat_proof = FALSE // For rglass-windowed airlocks and firedoors
 	var/emergency = FALSE
-
+	var/unres_sides = 0 //Unrestricted sides. A bitflag for which direction (if any) can open the door with no access
 	//Multi-tile doors
 	var/width = 1
 
@@ -55,6 +55,10 @@
 	..()
 	update_dir()
 
+/obj/machinery/door/power_change()
+	..()
+	update_icon()
+
 /obj/machinery/door/proc/update_dir()
 	if(width > 1)
 		if(dir in list(EAST, WEST))
@@ -175,10 +179,15 @@
 /obj/machinery/door/allowed(mob/M)
 	if(emergency)
 		return TRUE
+	if(unrestricted_side(M))
+		return TRUE
 	if(!requiresID())
 		return FALSE // Intentional. machinery/door/requiresID() always == 1. airlocks, however, == 0 if ID scan is disabled. Yes, this var is poorly named.
 	return ..()
 
+/obj/machinery/door/proc/unrestricted_side(mob/M) //Allows for specific side of airlocks to be unrestrected (IE, can exit maint freely, but need access to enter)
+	return get_dir(src, M) & unres_sides
+	
 /obj/machinery/door/proc/try_to_weld(obj/item/weldingtool/W, mob/user)
 	return
 

code/game/objects/effects/mapping_helpers.dm

@@ -67,6 +67,24 @@
 /obj/effect/mapping_helpers/no_lava
 	icon_state = "no_lava"
 
+/obj/effect/mapping_helpers/airlock
+	layer = DOOR_HELPER_LAYER
+
+/obj/effect/mapping_helpers/airlock/unres
+	name = "airlock unresctricted side helper"
+	icon_state = "airlock_unres_helper"
+
+/obj/effect/mapping_helpers/airlock/unres/Initialize(mapload)
+	..()
+	if(!mapload)
+		log_world("### MAP WARNING, [src] spawned outside of mapload!")
+		return
+	var/obj/machinery/door/airlock/airlock = locate(/obj/machinery/door/airlock) in src.loc
+	if(airlock)
+		airlock.unres_sides ^= dir
+	else
+		log_world("### MAP WARNING, [src] failed to find an airlock at [AREACOORD(src)]")
+		
 /obj/effect/mapping_helpers/no_lava/New()
 	var/turf/T = get_turf(src)
 	T.flags |= NO_LAVA_GEN