Add Rui's creeper mod code:

Forked from Git commit 036666e. Original repo & forum thread appear to
have been deleted.

spawn.lua

@@ -0,0 +1,32 @@
+minetest.register_abm({
+	nodenames = {"default:dirt_with_grass","default:stone"},
+	neighbors = {"air"},
+	interval = 30,
+	chance = 9000,
+	action = function(pos, node, _, active_object_count_wider)
+		if active_object_count_wider > 5 then
+			return
+		end
+		pos.y = pos.y+1
+		if not minetest.get_node_light(pos) then
+			return
+		end
+		if minetest.get_node_light(pos) > 5 then
+			return
+		end
+		if minetest.get_node_light(pos) < -1 then
+			return
+		end
+		if pos.y > 31000 then
+			return
+		end
+		if minetest.get_node(pos).name ~= "air" then
+			return
+		end
+		pos.y = pos.y+1
+		if minetest.get_node(pos).name ~= "air" then
+			return
+		end
+		minetest.add_entity(pos,"creeper:creeper")
+	end
+})