diff --git a/shutdown_notice/init.lua b/shutdown_notice/init.lua
new file mode 100644
index 0000000..224d48d
--- /dev/null
+++ b/shutdown_notice/init.lua
@@ -0,0 +1,67 @@
+-- twi_mods/shutdown_notice/init.lua
+-- shutdown notice
+-- Copyright (C) 2024  1F616EMO
+-- SPDX-License-Identifier: LGPL-3.0-or-later
+
+-- 2025年1月22日星期三 12:30:00 GMT+08:00
+local target_time = 1737520200
+local target_time_desc = "on 2025/01/22 at 12:30 UTC+8"
+local last_for = "8 hours, i.e. 2025/01/22 at 19:30 UTC+8"
+
+-- 2025年1月22日星期三 00:00:00 GMT+08:00
+local start_show = 1737475200
+
+local start_show = 0
+
+local gui = flow.widgets
+
+local function format_second(sec)
+    if sec < 0 then return "now" end
+    return string.format("in %d hours %d minutes %d seconds",
+        math.floor(sec / 3600), math.floor((sec % 3600) / 60), sec % 60)
+end
+
+local flow_gui = flow.make_gui(function()
+    return gui.Vbox {
+        max_w = 15,
+        gui.Label {
+            w = 15, h = 1.2,
+            expand = true, align_h = "centre",
+            label = "IMPORTANT NOTICE",
+            style = {
+                font_size = "*6",
+            },
+        },
+        gui.Box { w = 0.25, h = 0.25, color = "grey" },
+        gui.Textarea {
+            w = 15, h = 5,
+            default =
+                "To upgrade server hardware and move the data center, " ..
+                "the server will shut down " .. target_time_desc .. ", i.e. " ..
+                format_second(target_time - os.time()) .. ". The maintenance will last " ..
+                last_for .. ". Sorry for the inconvenience.",
+            style = {
+                font_size = "*2",
+            },
+        },
+        gui.ButtonExit {
+            w = 5, h = 2,
+            expand = true, align_h = "centre",
+            label = "OK",
+            style = {
+                font_size = "*2",
+            },
+        },
+    }
+end)
+
+core.register_on_joinplayer(function(a_player)
+    if os.time() > start_show then
+        core.after(0.3, function(name)
+            local player = core.get_player_by_name(name)
+            if player then
+                flow_gui:show(player)
+            end
+        end, a_player:get_player_name())
+    end
+end)
diff --git a/shutdown_notice/mod.conf b/shutdown_notice/mod.conf
new file mode 100644
index 0000000..5d9d103
--- /dev/null
+++ b/shutdown_notice/mod.conf
@@ -0,0 +1,2 @@
+name = shutdown_notice
+depends = flow