Started working on PoC.

.luacheckrc

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+globals = {"minetest", "ItemStack", "VoxelArea", "vector", "nodecore", "include", "SecureRandom"}
+color = false
+quiet = 1

.lualocals

@@ -0,0 +1,8 @@
+~print
+minetest
+ItemStack
+VoxelArea
+vector
+nodecore
+include
+SecureRandom

init.lua

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+-- LUALOCALS < ---------------------------------------------------------
+local math, minetest, os, pairs, setmetatable, string, tonumber
+    = math, minetest, os, pairs, setmetatable, string, tonumber
+local math_abs, math_ceil, os_date, string_format
+    = math.abs, math.ceil, os.date, string.format
+-- LUALOCALS > ---------------------------------------------------------
+
+local modname = minetest.get_current_modname()
+local modstore = minetest.get_mod_storage()
+
+local countdown = tonumber(minetest.settings:get(modname .. "_countdown")) or 10
+
+local data
+do
+	local raw = modstore:get_string("data")
+	raw = raw and minetest.deserialize(raw) or {}
+	data = {}
+	setmetatable(data, {
+			__index = raw,
+			__newindex = function(_, k, v)
+				raw[k] = v
+				modstore:set_string("data", minetest.serialize(raw))
+			end
+		})
+end
+
+local function deadworld()
+	if not data.date then return end
+	return string_format("\n\nThis world has been destroyed.\n\n"
+		.. "Player %q completed construction of a doomsday device"
+		.. " at %s on %s, and doomed us all.",
+		data.pname or "UNKNOWN",
+		data.pos and minetest.pos_to_string(data.pos) or "UNKNOWN",
+		data.date)
+end
+
+minetest.register_on_prejoinplayer(deadworld)
+
+local odds = {["default:mese"] = true}
+for i = 1, 8 do odds["nc_lux:cobble" .. i] = true end
+local evens = {
+	["default:diamond_block"] = true,
+	["nc_lode:block_tempered"] = true,
+	["nc_lode:block_annealed"] = true
+}
+
+local function recipecheck(pos)
+	for dx = -2, 2 do
+		for dy = -2, 2 do
+			for dz = -2, 2 do
+				local t = math_abs(dx) + math_abs(dy) + math_abs(dz)
+				if t < 3 then
+					local nn = minetest.get_node({
+							x = pos.x + dx,
+							y = pos.y + dy,
+							z = pos.z + dz
+						}).name
+					if nn == "ignore" then return end
+					if not (t == 2 and evens or odds)[nn] then return false end
+				end
+			end
+		end
+	end
+	return true
+end
+
+minetest.register_on_placenode(function(pos, newnode, placer)
+		if data.pos then return end
+		if not (odds[newnode.name] or evens[newnode.name]) then return end
+		for dx = -2, 2 do
+			for dy = -2, 2 do
+				for dz = -2, 2 do
+					if recipecheck({
+							x = pos.x + dx,
+							y = pos.y + dy,
+							z = pos.z + dz
+						}) then
+						data.pname = placer and placer.get_player_name and placer:get_player_name()
+						data.pos = pos
+						data.deadline = minetest.get_gametime() + countdown
+					end
+				end
+			end
+		end
+	end)
+
+local hud_whiteout = {}
+local hud_waypoint = {}
+
+minetest.register_on_leaveplayer(function(player)
+		local pname = player:get_player_name()
+		hud_whiteout[pname] = nil
+		hud_waypoint[pname] = nil
+	end)
+
+local function destroyworld(pos)
+	data.date = os_date()
+	data.pos = pos
+	local msg = deadworld()
+	for _, p in pairs(minetest.get_connected_players()) do
+		minetest.kick_player(p:get_player_name(), msg)
+	end
+end
+
+local function interval()
+	minetest.after(1, interval)
+
+	if not data.deadline then return end
+	local timeleft = data.deadline - minetest.get_gametime()
+
+	local alpha = math_ceil(timeleft / countdown * 255)
+	if alpha > 255 then alpha = 255 end
+	local txr = "[combine:1x1^[noalpha^[colorize:#ffffff:255^[opacity:" .. alpha
+
+	for _, p in pairs(minetest.get_connected_players()) do
+		local pname = p:get_player_name()
+	end
+end
+minetest.after(0, interval)