Hello and welcome to my guide. Just keep in mind that this walkthrough is not polished and can be improved in a lot of places (I forgot to open sewers to get AK-47 with Barry, missed some items and etc.). Also game decides what items to give you at the start of each chapter so you don't have to pick items at the end of chapter as I did (CountDown and Invisible Modes). Futher the No Escape Difficulty was completed with all skills maxes out, all parts found and equiped to the weapons.
Since these videos were made on Twitch and not specifically made for this guide so there is some discomfort. So if you want to watch video (without cutscenes or start from specific chapters) you have to fast forward to times I wrote in a guide above the video. Because Steam link to Youtube videos does not support custom Youtube URL's to the videos (so the video could start not at the beginning but from specific time) I added them manually (just press on the character's chapter if that's more comfortable for you).

Basically there is very little to advice. If you need tips then watch my average videos. I'll write only "not so obvious observations":

No Escape Difficulty

• Don't start it (unless you want a torture) unless you have all weapon upgrades and all skills maxed out.
  
• You shouldn't kill all the enemies because some minibosses fights and some areas can be rushed through or passed by safely if you'll play smart. Some examples: forest area can be rushed through with Natalie easily because enemies cannot grab her (only problem you might face that bot might stuck somewhere), also you can run past half of enemies in slaughterhouse in Claire Episode 3, second Dhurlga fight on Barry Episode 3 can be completely avoided if you have 1 (preferably 2) smoke bottles (you could see how I do this in the video) same as Dhurlga 1st fight in Barry Episode 4. By doing this you save ammo, save time, don't accidently decrease your accuracy if you miss some shots.
  
• Exploit Natalie's vision ability a lot.
  
• You'll want to kill all (except one) enemies in "water tanks" on Barry Episode 4 (like I did) if you want to play it safe.

CountDown Mode

• Don't save items (bottles) to much as I did. Game "decides" your equipment at every chapter (I noticed it only half-way through the CountDown Mode). For example: if you will not take AK-47 with Barry in Episode 3 you still start with AK-47 on chapter 4.
  
• I'd say Barry Episode 3 is the hardest because you have so little time (unless I missed a hourglass somewhere...). So rush as fast as you can, don't miss any hourglasses and save at least 2 smoke bottles for 2nd Dhurgla fight.
  
• Save at least one smoke bottle for Dhurgla fight in Barry Episode 4 otherwise that fight can take a lot of ammo or even retries.
  
• You should know all Glasps locations in the game for the obvious reasons.
  
• You'll want to kill all (except one) enemies in "water tanks" on Barry Episode 4. You're not only playing safe but increase your time reserves a lot (unless you're low on ammo but here I cannot help you).
  
• If you'd take most of assault rifle and magnum ammo in Barry Episode 4 and save around 90% of those for the final boss then it will be a piece of cake.
  
• You should know where most of the hidden (and not hidden) items locations are (sure some places have static hidden items like gems but some are random I think?).

Invisible Mode

• Exploit Natalie's vision ability a LOT.
  
• I highly suggest to play this mode with headphones so at least it's possible to know if enemy is near.
  
• Use tips from above (save ammo, smoke bottles, play safe with "water tanks", know hidden items locations and etc.).

Walkthoughs starts at these times:
Playlist here if you want to watch everything.
First Part:
Episode 1 Claire: 0:06:02
Episode 1 Barry: 0:30:52
Episode 2 Claire: 0:53:53
Episode 2 Barry: 1:28:26
Episode 3 Claire: 1:58:29
Second part:
And Claire Episode 3 continues in next video because Twitch uploads videos to Youtube maximum of 2 hours lenght.
Third part:
Episode 3 Barry: 0:05:08
Episode 4 Claire: 0:50:45
Episode 4 Barry: 1:08:45

Walkthoughs starts at these times:
Playlist here if you want to watch everything.
First Part:
Episode 1 Claire: 0:00:33
Episode 1 Barry: 0:17:05
Episode 2 Claire: 0:33:56
Episode 2 Barry: 0:59:43
Episode 3 Claire: 1:20:42
Episode 3 Barry: 1:54:45
And Barry Episode 3 continues in next video because Twitch uploads videos to Youtube maximum of 2 hours lenght.
Second part:
Episode 4 Claire: 0:21:38
Episode 4 Barry: 0:31:47

Walkthoughs starts at these times:
Playlist here if you want to watch everything.
First Part:
Episode 1 Claire: 0:00:10
Episode 1 Barry: 0:18:50
Episode 2 Claire: 0:40:22
Episode 2 Barry: 1:14:28
Second part:
Episode 3 Claire: 0:00:02
Episode 3 Barry: 0:46:08
Episode 4 Claire: 1:26:15
Episode 4 Barry: 1:36:42
And Barry Episode 4 continues in next video because Twitch uploads videos to Youtube maximum of 2 hours lenght.
Third part part:

Version 1.3 – 2015.03.24

• Noticed that Twitch Export to Youtube feature is a little buggy and cut out last few minutes of the Invisible Mode (Fixed) and 18 minutes of the CountDown Mode (Fixed).
  
• Replaced Invisible last video.
  
• Fixed replaced video times.
  
• Replaced CountDown last video.
  
• Fixed replaced video times.
  
• Added Some Advice section.
  
• Added Additional Notes section.
  
• Polished Guide a little (i. e. fixed grammar mistakes I noticed and etc.).

Version 1.1 – 2015.03.23

• Added Invisible Mode walkthrough.
  
• Added section of Guide Version.

Version 1.00 – 2015.03.22

• Created guide barebones.
  
• Added section of No Escape Difficulty walkthrough.
  
• Added No Escape Difficulty walkthrough.
  
• Added section of Countdown Mode walkthrough.
  
• Added Countdown Mode walkthrough.
  
• Added section of Invisible Mode walkthrough.

If you liked guide I'd appreciated if you could rate it at least.

Also since this is my first guide (don't really have time for this) all the criticism is welcome. If anyone wants to add something "not so obvious" to the "Some Advice" section I'm open to suggestions. Just post comment and I'll add it if it will be worth it when I'll have the time (of course credits will go to the post author).