Patrolled is the 138th level in Chip's Challenge Level Pack 2. Patrolled, originally made by Tyrethali Ansrath, is "patrolled" by tanks which switch themselves at specific intervals, which mix up the level significantly and force Chip to make plans ahead of time. Take the three yellow keys behind the socket, then go to the blue button on the right and switch twice, and then turn to the west and exit through the stream of yellow locks.