Perceptive Achievement Guide
Trigger 3 secret encounters with the bag-headed boy. They are well hidden.
The first one is right after you see the 3 slot for the gears, go to the bars at the right, wait a couple of seconds and he should show up.
The second rendezvous will be after the beginning of chapter two right after the turnstile. Walk to the left a little then tudrn back right and when you reach the turnstile again he appears.
The last meeting is in chapter 6 when you replace the generator with the compass After you picked up the leg at the right side go back to the generator, turn it off and the bag-headed boy will come out from that dark corner