What I disliked most about this game were the points of no return (PONR), which I often stumbled into when I wasn't yet ready to leave. But at the same time, I didn't want to use a walkthrough, as they contain a lot of spoilers. Maybe this guide can help some people who also like to explore everything on their own.

I put all the images in spoiler tags, so you can decide yourself how far ahead you want to look.

Temporary PONRs, which prevent you from going back, but allow you to return later on, are not listed here. If you find any PONRs I missed, let me know in the comments section :)

Entering the elevator after collecting the items from your office.


Opening your car.

Using the elevator at the dam.


Hint: Make sure you complete the switchyard breaker, before proceeding.


Going through flood door 02.

The "house" in the canal can be a PONR if you haven't yet reached door B1 (see below).


Next there are two possible PONRs:

a) Door B1


b) Door D4


Both are followed by several PONR. Once you have taken the elevator up, there are the following two to look out for:

a) Taking the orange pipe.


b) Do some parkour, but be careful, it's quite deadly.


Stepping onto the raft.


Hint: Not a PONR, but it might make your life easier if you open A3 before going through the gate.


Before continuing over the planks, make sure you have found an alternate path to the door (right picture).
Technically not a PONR, as you can get back with enough persistence. But it might take you several deaths.


Possible PONR: After going through door C5, don't take a leap of faith, without first opening the gate (left picture).

Possible PONR: Don't take the "lift", without picking up the key first.


Flipping the high voltage main switch.


Taking the elevator up.


Taking the lift down.


After leaving the office building, walking through door 02.

After the Pitheath Water Treatment Plant, walking through the door (right picture).


Inside the building (left picture), using the metro maintenance access.


In the sewer going through the door (right picture); followed by several PONRs.

Jumping down, behind the barrier.


Taking the train.


Jumping down, after climbing through the duct.


Walking along a red and white pipe, after taking the spiral staircase.


Driving the train through gate 02.


Driving the train through the "Central Metro Station" gate.


Walking out of a duct into a ventilation shaft. Immediately followed by another PONR.


Jumping out of a vent onto the escalator.

Getting past the locked door.


Closing the blast door.


After taking a coffee break, jumping down a broken bridge.


Walking through the automatically closing flood door.


Possible PONR: Before going through gate 4 (left picture), explore the tracks further and park close to the door to keep it open (right picture).


At the coal conveyer belt, jumping onto the spiral staircase structure.


Walking through the sliding door.


After following the instructions, flipping the switch for "Boiler 2".

I'm currently replaying the game and making pictures of all the PONRs. Once I collected all for Act 3, I will continue this guide.