Time for some answers. The next page of the guide contains walkthroughs for chapters 16 and 17 of Blair Witch. They serve as an epilogue to the story and will summarise your choices made throughout the whole game.
This is the last time you visit the camp. There is a tape on the rock. Play it back, and you will learn that the boy has managed to get into the house. It will also turn out that he is on the hill, not far. Go to him and go inside.
Your task is to get to the basement. The entrance is under the stairs. Unfortunately, the door will be closed. The key can be found in a room at the highest level of the building. When you pick it up, you can go downstairs and enter the basement.
Now, you need to follow the only available road until you come across a door with a witch symbol. Unfortunately, the door is closed. Continue forward and enter the hole in the wall. There you will find a tape that will allow you to open the door.
Follow the marked route. Along the way, you'll receive a SMS from Jess. Suddenly, you will encounter two monsters. You have to get past them in such a way so they aren't hit with light rays.
Follow the indicated path. At some point you will start to see objects related to Eliss's past.
While moving forward along the only available path (you'll encounter a totem, and will have to make a decision whether to listen to the witch) you'll soon reach the corridor from the movie. You have to rewind it so that you first pass through a clear corridor and then make a hole in the wall to continue.
Continue along the only available way. Avoid the monster encountered on the road. This way, you'll reach a room with military memorabilia. Look at the photo lying on the box and continue forward.
Continue along the only available path, while avoiding monsters along the way. Finally, you'll reach a room containing the final tape. After playing it back, move to the same corridor as seen on the recording and point the camera at the wall until the witch goes away. Now all is left to do is to continue down the path. You'll finally reach the basement.
You'll encounter a hatch. Try opening it. It turns out it is locked. You will find the key on the table with the photos.
Open the hatch and climb inside to activate the final cutscene and end the game.