diff --git a/mods/hades_bounds/init.lua b/mods/hades_bounds/init.lua
new file mode 100644
index 0000000..cb94ad4
--- /dev/null
+++ b/mods/hades_bounds/init.lua
@@ -0,0 +1,130 @@
+local S = minetest.get_translator("hades_bounds")
+
+local players_out_of_bounds = {}
+local players_out_of_bounds_blinding = {}
+
+local has_death_messages_mod = minetest.get_modpath("hades_death_messages") ~= nil
+
+-- Minetest world boundaries, as of 5.4.1
+local END_MAX = 30927
+local END_MIN = -30912
+
+-- Where the player starts to take damage
+local BOUNDARY_DIFF = 500.5
+-- Where the textual out-of-bounds warning appears
+local BOUNDARY_WARNING_DIFF = BOUNDARY_DIFF + 50
+-- Where the out-of-bounds "green radiation warning screen" appears
+local BOUNDARY_WARNING_DIFF_2 = BOUNDARY_DIFF + 20
+-- At which time interval (in seconds) the player takes radiation damage
+local BOUNDARY_TIME_CHECK = 1
+-- Every how many blocks the radiation damage increases
+local BOUNDARY_DAMAGE_INCREASE = 50
+-- Maximum boundary damage to deal
+local BOUNDARY_MAX_DAMAGE = 4
+
+local timer = 0
+
+local function out_of_bounds(pos, diff)
+	local boundary_min = END_MIN + diff
+	local boundary_max = END_MAX - diff
+	return pos.x > boundary_max or pos.x < boundary_min or pos.z > boundary_max or pos.z < boundary_min or pos.y > boundary_max
+end
+local function out_of_bounds_farthest(pos, diff)
+	local boundary_min = END_MIN + diff
+	local boundary_max = END_MAX - diff
+	local dists = {
+		pos.x - boundary_max,
+		pos.x - boundary_min,
+		pos.z - boundary_max,
+		pos.z - boundary_min,
+		pos.y - boundary_max,
+	}
+	local far = -1
+	for d=1, #dists do
+		if math.abs(dists[d]) > far then
+			far = dists[d]
+		end
+	end
+	return far
+end
+
+minetest.register_globalstep(function(dtime)
+	timer = timer + dtime
+	if timer < BOUNDARY_TIME_CHECK then
+		return
+	end
+	timer = 0
+	local players = minetest.get_connected_players()
+	for p=1, #players do
+		local player = players[p]
+		local name = player:get_player_name()
+		local pos = player:get_pos()
+		local creative = minetest.is_creative_enabled(name)
+		if not creative and out_of_bounds(pos, BOUNDARY_WARNING_DIFF) then
+			local oob = out_of_bounds(pos, BOUNDARY_DIFF)
+			local text, img
+			if oob then
+				text = S("WARNING: Critically high radiation!")
+				img = "hades_bounds_screen_radiation_full.png"
+			else
+				text = S("WARNING: High radiation!")
+				if out_of_bounds(pos, BOUNDARY_WARNING_DIFF_2) then
+					img = "hades_bounds_screen_radiation_warn.png"
+				end
+			end
+			if not players_out_of_bounds[name] then
+				local hudid = player:hud_add({
+					hud_elem_type = "text",
+					text = text,
+					position = { x = 0.5, y = 0.2 },
+					number = 0xFFFF00,
+					z_index = 100,
+					scale = { x = 100, y = 100 },
+					size = { x = 2, y = 2 },
+				})
+				players_out_of_bounds[name] = hudid
+			else
+				player:hud_change(players_out_of_bounds[name], "text", text)
+			end
+			if img and not players_out_of_bounds_blinding[name] then
+				local hudid = player:hud_add({
+					hud_elem_type = "image",
+					text = img,
+					position = { x = 0.5, y = 0.5 },
+					number = 0xFFFF00,
+					z_index = -400,
+					scale = { x = -100, y = -100 },
+				})
+				players_out_of_bounds_blinding[name] = hudid
+			elseif img then
+				player:hud_change(players_out_of_bounds_blinding[name], "text", img)
+			end
+			local hp = player:get_hp()
+			if oob and hp > 0 then
+				local how_deep_in = out_of_bounds_farthest(pos, BOUNDARY_DIFF)
+				local dmg = math.min(BOUNDARY_MAX_DAMAGE, math.max(1, math.floor(how_deep_in / BOUNDARY_DAMAGE_INCREASE)))
+				if has_death_messages_mod then
+					hades_death_messages.player_damage(player, S("Radiation poisoning"))
+				end
+				player:set_hp(hp - dmg)
+			end
+		else
+			if players_out_of_bounds[name] then
+				player:hud_remove(players_out_of_bounds[name])
+				players_out_of_bounds[name] = nil
+			end
+		end
+		if creative or not out_of_bounds(pos, BOUNDARY_WARNING_DIFF_2) then
+			if players_out_of_bounds_blinding[name] then
+				player:hud_remove(players_out_of_bounds_blinding[name])
+				players_out_of_bounds_blinding[name] = nil
+			end
+		end
+	end
+end)
+
+minetest.register_on_leaveplayer(function(player)
+	local name = player:get_player_name()
+	players_out_of_bounds[name] = nil
+	players_out_of_bounds_blinding[name] = nil
+end)
diff --git a/mods/hades_bounds/mod.conf b/mods/hades_bounds/mod.conf
new file mode 100644
index 0000000..13cbac1
--- /dev/null
+++ b/mods/hades_bounds/mod.conf
@@ -0,0 +1,3 @@
+name = hades_bounds
+description = Deals radiation damage to players who ventured too far
+optional_depends = hades_death_messages
diff --git a/mods/hades_bounds/textures/hades_bounds_screen_radiation_full.png b/mods/hades_bounds/textures/hades_bounds_screen_radiation_full.png
new file mode 100644
index 0000000..233ffc1
Binary files /dev/null and b/mods/hades_bounds/textures/hades_bounds_screen_radiation_full.png differ
diff --git a/mods/hades_bounds/textures/hades_bounds_screen_radiation_warn.png b/mods/hades_bounds/textures/hades_bounds_screen_radiation_warn.png
new file mode 100644
index 0000000..bc99b80
Binary files /dev/null and b/mods/hades_bounds/textures/hades_bounds_screen_radiation_warn.png differ