initial

code/modules/admin/game_master/game_master.dm

@@ -58,6 +58,7 @@ GLOBAL_VAR_INIT(radio_communication_clarity, 100)
 	var/list/submenu_types = list(
 		/obj/structure/pipes/vents = /datum/game_master_submenu/ambush/vents,
 		/obj/structure/tunnel = /datum/game_master_submenu/ambush/tunnels,
+		/mob/living/carbon/human = /datum/game_master_submenu/infest,
 	)
 
 	/// List of current submenus

code/modules/admin/game_master/game_master_submenu/infest.dm

@@ -0,0 +1,98 @@
+#define DEFAULT_SPAWN_HIVE_STRING XENO_HIVE_NORMAL
+
+/datum/game_master_submenu/infest
+	tgui_menu_name = "GameMasterSubmenuInfest"
+	tgui_menu_title = "Infest Control"
+
+	/// Current selected hive for the embryo
+	var/selected_hive = DEFAULT_SPAWN_HIVE_STRING
+
+	/// Target growth stage for the embryo
+	var/embryo_stage = 0
+
+/datum/game_master_submenu/infest/ui_data(mob/user)
+	. = ..()
+
+	var/list/data = list()
+
+	data["selected_hive"] = selected_hive
+	data["embryo_stage"] = embryo_stage
+
+	return data
+
+/datum/game_master_submenu/infest/ui_static_data(mob/user)
+	. = ..()
+
+	var/list/data = list()
+
+	data["selectable_hives"] = ALL_XENO_HIVES
+
+	return data
+
+/datum/game_master_submenu/infest/ui_act(action, list/params, datum/tgui/ui, datum/ui_state/state)
+	. = ..()
+
+	switch(action)
+		if("set_selected_hive")
+			selected_hive = params["new_hive"]
+			return TRUE
+
+		if("set_embryo_stage")
+			embryo_stage = params["stage"]
+			return TRUE
+
+		if("infest")
+			setup_embryo()
+			return TRUE
+
+		if("clear_infest")
+			remove_embryo()
+			return TRUE
+
+		if("burst")
+			force_burst()
+			return TRUE
+
+/datum/game_master_submenu/infest/proc/setup_embryo()
+	var/obj/item/alien_embryo/infesting_embryo
+	for(var/obj/item/alien_embryo/embryo in referenced_atom) //if this hive's embryo already exists, convert to larva and use it
+		if(embryo.hivenumber == selected_hive)
+			infesting_embryo = embryo
+		else
+			qdel(embryo)
+
+	if(!infesting_embryo) //else, make a new one
+		infesting_embryo = new /obj/item/alien_embryo(referenced_atom)
+		infesting_embryo.hivenumber = selected_hive
+
+		var/mob/living/carbon/human/infested_host = referenced_atom
+		infesting_embryo.hugger_ckey = infested_host.ckey
+
+		GLOB.player_embryo_list += infesting_embryo
+		infested_host.species?.larva_impregnated(infesting_embryo) //Yautja handling
+
+	infesting_embryo.stage = embryo_stage
+
+/datum/game_master_submenu/infest/proc/remove_embryo()
+	for(var/obj/item/alien_embryo/embryo in referenced_atom)
+		qdel(embryo)
+
+/datum/game_master_submenu/infest/proc/force_burst()
+	var/mob/living/carbon/xenomorph/larva/infesting_larva = locate() in referenced_atom //if a larva already exists, use it
+
+	if(!infesting_larva) //else if this hive's embryo already exists, convert to larva and use it
+		for(var/obj/item/alien_embryo/embryo in referenced_atom)
+			if(embryo.hivenumber == selected_hive)
+				embryo.become_larva()
+				infesting_larva = locate() in referenced_atom
+				break
+
+	if(!infesting_larva) //else, make a new larva
+		infesting_larva = new /mob/living/carbon/xenomorph/larva(referenced_atom, null, selected_hive)
+
+		var/mob/living/carbon/human/infested_host = referenced_atom
+		infesting_larva.ckey = infested_host.ckey
+
+	infesting_larva.chest_burst(referenced_atom)
+
+#undef DEFAULT_SPAWN_HIVE_STRING

colonialmarines.dme

@@ -1390,6 +1390,7 @@
 #include "code\modules\admin\game_master\extra_buttons\toggle_join_xeno.dm"
 #include "code\modules\admin\game_master\extra_buttons\toggle_vehicle_blockers.dm"
 #include "code\modules\admin\game_master\game_master_submenu\ambush.dm"
+#include "code\modules\admin\game_master\game_master_submenu\infest.dm"
 #include "code\modules\admin\game_master\game_master_submenu\tunnels.dm"
 #include "code\modules\admin\game_master\game_master_submenu\vents.dm"
 #include "code\modules\admin\medal_panel\medals_panel.dm"

tgui/packages/tgui/interfaces/GameMasterSubmenuInfest.js

@@ -0,0 +1,85 @@
+import { useBackend } from '../backend';
+import { Stack, Dropdown, Button, Section, Slider } from '../components';
+import { Window } from '../layouts';
+
+export const GameMasterSubmenuInfest = (props, context) => {
+  const { data, act } = useBackend(context);
+
+  return (
+    <Window width={400} height={400}>
+      <Window.Content scrollable>
+        <Stack direction="column" vertical>
+          <GameMasterSubmenuInfestInfestingPanel />
+        </Stack>
+      </Window.Content>
+    </Window>
+  );
+};
+
+export const GameMasterSubmenuInfestInfestingPanel = (props, context) => {
+  const { data, act } = useBackend(context);
+
+  return (
+    <Section title="Infesting">
+      <Stack direction="column" vertical>
+        <Stack.Item>
+          <Stack>
+            <Stack.Item>
+              <Dropdown
+                options={data.selectable_hives}
+                selected={data.selected_hive}
+                width="15rem"
+                onSelected={(new_hive) => {
+                  act('set_selected_hive', { new_hive });
+                }}
+              />
+            </Stack.Item>
+          </Stack>
+        </Stack.Item>
+        <Stack.Item mt={1}>Embryo Stage</Stack.Item>
+        <Stack.Item>
+          <Slider
+            maxValue={5}
+            minValue={0}
+            stepPixelSize={40}
+            value={data.embryo_stage}
+            onChange={(e, stage) => {
+              act('set_embryo_stage', { stage });
+            }}
+          />
+        </Stack.Item>
+        <Stack.Item>
+          <Stack>
+            <Stack.Item>
+              <Button
+                middle
+                content="Set"
+                onClick={() => {
+                  act('infest');
+                }}
+              />
+            </Stack.Item>
+            <Stack.Item>
+              <Button
+                middle
+                content="Clear"
+                onClick={() => {
+                  act('clear_infest');
+                }}
+              />
+            </Stack.Item>
+          </Stack>
+        </Stack.Item>
+        <Stack.Item>
+          <Button
+            middle
+            content="Burst Now"
+            onClick={() => {
+              act('burst');
+            }}
+          />
+        </Stack.Item>
+      </Stack>
+    </Section>
+  );
+};