Chapter 4 in Dark, the game, begins after Eric deals with Steiner at the end of Chapter 3.
While escaping the nightclub, Eric tries to contact Rose but she doesn’t answer; therefore, you will be asked to reach the Sanctuary.
As you cross the citys streets towards the Sanctuary, you will encounter new opponents, more powerful than those you fought up to this point.
Erics skills as a vampire play a vital role; therefore, you have to make sure that you collect as many hidden PDAs as possible, in order to level up faster.
The first Dark PDA collectible in Chapter 4 is located in the starting area, where you have to defeat the armored vampire hunters. Make sure that after you take them out, you look for a small office/chamber on the right side of the street (while facing the waypoint), and on a table inside the said chamber you will find the collectable.
The chamber is similar to a dead end, and it is located behind a trashcan. Move down the street to get the next PDA.
As you cross the street between the previous area and the next waypoint, Rose will contact you to tell you that the vampires are pinned down inside the club.
When you receive the phone call, stop and look on the left side of the street for another dead end and a trashcan. Search the area behind the trashcan to find the hidden PDA, and then continue to advance.
PDA 3 & PDA 4
The next two PDAs in Chapter 4 are in the plaza where the vampire hunters have placed the sensors to detect your presence. First, take them out while staying away from the sensors, then while facing the waypoint you should see a surveillance camera that scans the area.
The first PDA is under the camera, while for the second one, you have to check the left side of the street (standing in front of the camera) and look for a sustaining pillar, behind a large brown crate. Now, go inside the demolished building.
When you enter the demolished theater, make sure you go up on the ramp in front in front of you. Eventually, you will encounter a ghoul and next to it, on the right, is the PDA, on a crate.
Take it and remain on the same floor.
After you find the fifth PDA, follow the corridor near the crate where the collectible was located (right side) and turn left to trigger a cutscene showing several soldiers killing a ghoul. After the cutscene, turn left again and you will see another corridor that leads to a dead end.
Follow the corridor and you will find a mattress on the ground and the sixth Dark video game PDA.
While trying to find a way towards the Sanctuary, you will reach another plaza where the vampire hunters installed an UV generator that can kill you.
Pay close attention to the sounds you make and kill all enemies in the area. The PDA is on the right side of the plaza, as you enter the area, in a dead-end (the side opposed to the waypoint marked on your HUD).
For the eighth Dark collectible, you need to cross another plaza, after you pick up the previous PDA. Notice that in the middle of the area is a surveillance camera hidden between the trees, and the exit point is in a building on the left side, as you enter.
After you kill all enemies, dont approach the waypoint. Instead, turn right while facing it and you should see an alley. Go down the alley, and on the left side is a kiosk/office. Look behind it for the collectable, and then return to the waypoint.
PDA 9 & PDA 10
The final two Dark video game PDAs in Chapter 4 are inside the ruins of Sanctuary. Since you already know the place, they can be found faster, but you have to be aware that if you kill the boss in the middle of the club, you will trigger the final cutscene, thus you will miss the collectibles.
You will find the ninth PDA in the room where the DJ was mixing (left side, second floor, while looking at the soldier on the ground); and the last PDA is locate in a room on the second floor, but on the right side.
To reach the room you have to follow the stairs on the other side, without alerting the large soldier downstairs.
Make sure you pick both collectibles before taking him out, or you will have to load the last save. Chapter 5 also includes a series of collectibles you must find.