Adds some random asteroid dungeons (#5052)

code/game/objects/structures/sarcophagus.dm

@@ -0,0 +1,78 @@
+/obj/structure/sarcophagus
+	name = "sarcophagus"
+	desc = "A sealed ancient sarcophagus."
+	icon = 'icons/obj/sarcophagus.dmi'
+	icon_state = "sarcophagus"
+	density = 1
+	anchored = 0
+	var/open = FALSE
+
+/obj/structure/sarcophagus/examine(mob/user)
+	..()
+	if(!open)
+		to_chat(user, "\The [src]'s lid is closed shut.")
+	else
+		to_chat(user, "\The [src]'s lid is open.")
+
+/obj/structure/sarcophagus/Initialize()
+	. = ..()
+	if(prob(25))
+		desc = "Don't open it."
+
+/obj/structure/sarcophagus/update_icon()
+	if(open)
+		icon_state = "sarcophagus_open"
+	else
+		icon_state = initial(icon_state)
+
+/obj/structure/sarcophagus/ex_act(severity)
+	switch(severity)
+		if(1.0)
+			qdel(src)
+		if(2.0)
+			if(prob(50))
+				qdel(src)
+		if(3.0)
+			if(prob(25))
+				open()
+	return
+
+/obj/structure/sarcophagus/attackby(obj/item/I as obj, mob/user as mob)
+	if(open)
+		return
+	if(istype(I, /obj/item/sarcophagus_key))
+		to_chat(usr, "<span class='notice'>You slide \the [I] inside an opening in \the [src].</span>")
+		open()
+
+/obj/structure/sarcophagus/proc/open()
+	playsound((get_turf(src)), 'sound/effects/stonedoor_openclose.ogg', 100, 1)
+	open = TRUE
+	update_icon()
+
+	if(prob(25))
+		explosion(get_turf(src), 2, 3, 4, 4)
+		qdel(src)
+		return
+
+	var/outcomes = pick("remains", "xenoarch", "highvalue", "supermatter", "artifact", "beyond")
+	switch(outcomes)
+		if("remains")
+			new /obj/effect/decal/remains/xeno (get_turf(src))
+		if("xenoarch")
+			new /obj/item/weapon/archaeological_find (get_turf(src))
+		if("highvalue")
+			new /obj/random/highvalue (get_turf(src))
+		if("supermatter")
+			new /obj/machinery/power/supermatter/shard (get_turf(src))
+		if("artifact")
+			new /obj/machinery/artifact (get_turf(src))
+		if("beyond")
+			new /obj/machinery/from_beyond (get_turf(src))
+	return
+
+/obj/item/sarcophagus_key
+	name = "ancient key"
+	desc = "An archaic key, probably not used to open any airlock on station."
+	icon = 'icons/obj/xenoarchaeology.dmi'
+	icon_state = "unknown1"
+	w_class = 2