Firstly, found a way to make a screenshot for your game. It can be a hotkey, integrated into this game by developers, other program, like Fraps or Yandex.Disk, hook for PrintScrean key and other...
For example, Arcanum uses the F12 key for capturing screenshots. It can freeze the game by some time for large screen resolution, so be carefull. Capture two or three pictures for testing.

Second time, determinate a path for the folder with screenshots. For example, full path for default Arcanum from store is:


I am using modification Arcanum Multiverse Edition without SierraLauncher, so my path is:


I will use default path for this guide, so, if you found mistake with paths - it is just my carelessness.
How you can found this path? Browse local files on game settings from Steam client.

Next, we need a game identificator for Steam. It can be found from url-string for this game in the Steam Store. For example, Arcanum has this url:
(text contains spaces, sorry) and id is:

The last for us is the folder for screenshots. It has an unique path for each user, for example I have:
How to found it? Select any game from your library, view screenshots by Steam Screenshots menu and browse screenshot on local drive. Up by file hierarchy two times and found this folder.

Now, we have full needed information. Next we will create folders:

The folder with screenshots - go by the content path (ended by remote) and create here new folder with game id, after that create the folder with screenshots name. Go into and create the new folder for previews with thumbnails name. For example, I have:

Path for screenshots:
Path for previews:

We also need a folder where our script for screenshoting will be. I created folder here:
but you can use any other place

Our screenshots will be automatically converted into JPEG, renamed and copied into destination folder. But we need one program for conversion and preview creation. It is a free program ImageMagic. Binaries can be download from http://www.imagemagick.org/script/download.php

For 64-bit Windows select (version can be different):

For 32-bit Windows select (version can be different):

Download the latest portable version for your system!

After that extract download archive into the subfolder im of our script folder. The full path for this tool will same as:

Open the Notepad and write same script:


and save it with .bat extension into the our script folder. Full path for it will be, for example, as:

What about this script? Firstly - two lines with settings for good script work. After that - block with variables:

• Line for tool for screenshot converting.
  
• Line for folder with screenshots.
  
• Line for output directory with screenshots.
  
• Line for output directory for previews.
  
• Lines with resolution, extenstion and special VR suffix (we need a copy of screenshot for VR, sad).

Next line contains the current date and time for naming screenshots. Steam can use only this format.

Next lines find, convert and copy screenshots, and create VR copies and previews. Last line - remove originals. If you do not need remove them (for example - during testing) - just do not write this line.
At the end - pause until any key pressing.

You need to modificate this script for your game (if it is not Arcanum) and for your folders. Also, this script contains this construction:
This element search .bmp pictures and use them, but if your game or tool saves screenshots with over format (.jpeg, .png ...) - just replace it. If your folder contains only screenshots (for Arcanum it is not true) - you can use this part:

Now, you can start script and check result! Game screenshots will be created with previews inside the Steam folders.

Or other folder with Admin restrictions - we need to create a link for our script and run it as Administrator. It can be managed on the link settings - after that run only this link!

Also we need to change the path of convertion tool for full path. Example here:

• You need to change this script for you! Without changes it is not working!
  
• Steam will find new screenshots only after restarting Steam Client!
  ONLY AFTER RESTART!
  
• Information about not-automatised creation of screenshots was founded here:
  http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=518072312
  
• Russian guide for Gothic can be found here:
  http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=632313065

At the end...
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1280836189

• Winged Hussar, I found a little mistake with spaces