diff --git a/init.lua b/init.lua
index 40b0a98..22d1d91 100644
--- a/init.lua
+++ b/init.lua
@@ -22,5 +22,6 @@ dofile(MP.."/mapgen.lua")
 dofile(MP.."/skybox.lua")
 dofile(MP.."/vacuum.lua")
 dofile(MP.."/marble.lua")
+--dofile(MP.."/light_restore.lua")
 
 print("[OK] Planet: mars (start: " .. planet_mars.y_start .. ", height:" .. planet_mars.y_height .. ")")
diff --git a/light_restore.lua b/light_restore.lua
new file mode 100644
index 0000000..e919977
--- /dev/null
+++ b/light_restore.lua
@@ -0,0 +1,46 @@
+-- proof of concept light restore
+-- XXX: unstable, unfinished, things may explode
+
+local c_air = minetest.get_content_id("air")
+local c_airlight = minetest.get_content_id("planet_mars:airlight")
+
+local timer = 0
+
+minetest.register_globalstep(function(dtime)
+	timer = timer + dtime
+	if timer < 2 then
+    return
+  end
+  timer = 0
+
+	print("light recalc")
+	for _, player in ipairs(minetest.get_connected_players()) do
+    -- TODO: check if player is in mars and in a cave (perlin noise)
+    local pos = player:get_pos()
+    local distance = 8
+
+		local pos1 = vector.subtract(pos, distance)
+		local pos2 = vector.add(pos, distance)
+
+		local manip = minetest.get_voxel_manip()
+	  local minp, maxp = manip:read_from_map(pos1, pos2)
+	  local area = VoxelArea:new({MinEdge=minp, MaxEdge=maxp})
+
+    local data = manip:get_data()
+
+		for z=minp.z,maxp.z do
+		for y=minp.y,maxp.y do
+		for x=minp.x,maxp.x do
+			local index = area:index(x,y,z)
+      if data[index] == c_air then
+        data[index] = c_airlight
+      end
+		end --x
+		end --y
+		end --z
+
+    manip:set_data(data)
+		manip:write_to_map()
+
+	end
+end)