LZ fog before first drop and sentryguns to guard agains early FOB rush (they last only ten minits)

code/game/objects/structures/blocker.dm

@@ -61,6 +61,26 @@
 	attack_hand(M)
 	return XENO_NONCOMBAT_ACTION
 
+GLOBAL_LIST_INIT(landing_zone_fog, list())
+/obj/structure/blocker/landing_zone_fog
+	name = "dense fog"
+	desc = "It looks way too dangerous to traverse. Best wait until it has cleared up."
+	icon = 'icons/effects/effects.dmi'
+	icon_state = "smoke"
+	opacity = TRUE
+
+/obj/structure/blocker/landing_zone_fog/Initialize()
+	GLOB.landing_zone_fog += src
+	. = ..()
+
+/obj/structure/blocker/landing_zone_fog/proc/clear()
+	GLOB.landing_zone_fog -= src
+	QDEL_IN(src, rand(3 SECONDS,5 SECONDS))
+
+/obj/structure/blocker/landing_zone_fog/Destroy()
+	GLOB.landing_zone_fog -= src
+	. = ..()
+
 
 /obj/structure/blocker/forcefield
 	name = "forcefield"
@@ -100,21 +120,16 @@
 
 	if(!visible)
 		invisibility = 101
-
-
 /obj/structure/blocker/forcefield/vehicles
 	types = list(/obj/vehicle/)
 
-
 /obj/structure/blocker/forcefield/vehicles/handle_vehicle_bump(obj/vehicle/multitile/multitile_vehicle)
 	if(multitile_vehicle.vehicle_flags & VEHICLE_BYPASS_BLOCKERS)
 		return TRUE
 	return FALSE
-
 /obj/structure/blocker/forcefield/multitile_vehicles
 	types = list(/obj/vehicle/multitile/)
 
-
 /obj/structure/blocker/forcefield/multitile_vehicles/handle_vehicle_bump(obj/vehicle/multitile/multitile_vehicle)
 	if(multitile_vehicle.vehicle_flags & VEHICLE_BYPASS_BLOCKERS)
 		return TRUE

code/modules/defenses/sentry.dm

@@ -467,6 +467,47 @@
 
 	fire(target)
 
+GLOBAL_LIST_INIT(landing_zone_sentryguns, list())
+/obj/structure/machinery/defenses/sentry/landing_zone
+	name = "UA-577 Gauss Turret spaceborn"
+	fire_delay = 2
+	omni_directional = TRUE
+	immobile = TRUE
+	turned_on = TRUE
+	icon_state = "premade" //for the map editor only
+	faction_group = FACTION_LIST_MARINE
+	placed = 1
+	var/first_warning = 9 MINUTES
+	var/second_warning = 9 MINUTES + 30 SECONDS
+	var/third_warning = 9 MINUTES + 57 SECONDS
+
+/obj/structure/machinery/defenses/sentry/landing_zone/Initialize()
+	GLOB.landing_zone_sentryguns += src
+	. = ..()
+
+/obj/structure/machinery/defenses/sentry/landing_zone/Destroy()
+	GLOB.landing_zone_sentryguns -= src
+	. = ..()
+/obj/structure/machinery/defenses/sentry/landing_zone/proc/on_landing()
+	GLOB.landing_zone_sentryguns -= src
+	addtimer(CALLBACK(src,PROC_REF(time_left), 1), first_warning)
+	addtimer(CALLBACK(src,PROC_REF(time_left), 2), second_warning)
+	addtimer(CALLBACK(src,PROC_REF(time_left), 3), third_warning)
+	QDEL_IN(src, 10 MINUTES)
+
+/obj/structure/machinery/defenses/sentry/landing_zone/proc/time_left(counter)
+	switch(counter)
+		if(1)
+			playsound(loc, 'sound/weapons/smg_empty_alarm.ogg', 15, 1)
+			visible_message(SPAN_WARNING("\The [name] beeps steadily as its battery gets low."))
+		if(2)
+			playsound(loc, 'sound/weapons/smg_empty_alarm.ogg', 20, 1)
+			visible_message(SPAN_WARNING("\The [name] beeps steadily as its battery gets criticly low."))
+		if(3)
+			playsound(loc, 'sound/mecha/critdestrsyndi.ogg', 25, 1)
+			visible_message(SPAN_WARNING("\The [name] deconstructs itself as its battery goes out!"))
+
+
 /obj/structure/machinery/defenses/sentry/premade
 	name = "UA-577 Gauss Turret"
 	immobile = TRUE
@@ -530,6 +571,8 @@
 	fire_delay = 4
 	omni_directional = TRUE
 
+
+
 //the turret inside the shuttle sentry deployment system
 /obj/structure/machinery/defenses/sentry/premade/dropship
 	density = TRUE

code/modules/shuttle/shuttles/dropship.dm

@@ -261,6 +261,12 @@
 		xeno_announcement(SPAN_XENOANNOUNCE("The dropship has landed."), "everything")
 		xeno_announce = FALSE
 
+	for(var/obj/structure/blocker/landing_zone_fog/fog as anything in GLOB.landing_zone_fog)
+		fog.clear()
+
+	for(var/obj/structure/machinery/defenses/sentry/landing_zone/sentrygun as anything in GLOB.landing_zone_sentryguns)
+		sentrygun.on_landing()
+
 /obj/docking_port/stationary/marine_dropship/on_dock_ignition(obj/docking_port/mobile/departing_shuttle)
 	. = ..()
 	turn_on_landing_lights()