add something to readme

README

@@ -1,6 +1,8 @@
 It's early in the morning and your alarm clock wakes you up. Unfortunately
 you don't remember where you put the alarm clock, so you have to run
-through your house to find it and shut if off.
+through your house to find it and shut if off. Listen to the sound wave
+which comes from the alarm clock. It will help you to find it, because
+the sound get lauder when you get closer.
 
 To play the game you need to serve the game from a web server and open
 the index.html with a browser.