27 days ago - AndrewT - Direct link
In the game launcher please set Display mode to windowed. THEN go here:

The latest supported Visual C++ downloads

This article lists the download links for the latest versions of Visual C++. support.microsoft.com support.microsoft.com And run the x86 and x64 installers there.


IF that doesn't help, Has the game ever run OK on this computer? Or never?

IF NEVER:
Install ALL these Microsoft modules:

Download Microsoft Visual C++ 2010 Service Pack 1 Redistributable Package MFC Security Update from Official Microsoft Download Center

www.microsoft.com www.microsoft.com

Download Microsoft Visual C++ 2015 Redistributable Update 3 RC from Official Microsoft Download Center

www.microsoft.com www.microsoft.com

Download DirectX End-User Runtimes (June 2010) from Official Microsoft Download Center

www.microsoft.com www.microsoft.com (run dxsetup.exe after extracting from this download)

Add CK3.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.


IF IT USED TO WORK:
Please do a full **clean** re-install:

- move any valued save games elsewhere
- "uninstall" in Steam-CK3
- manually delete both the Steam/SteamApps/common/CK3 AND Documents/Paradox Interactive/CK3 folders
- re-install game in Steam, run a Steam Verify when done.
- add CK3.exe to the exceptions list of your antivirus app; ESPECIALLY if you have Windows Defender, add it to the Ransomware "Apps Allowed Through" list.
- start the game with no mods active and test

In particular make sure there are no files or folders left under either the Steam CK3 or Documents CK3 locations, before installing again.


If those don't help:
DXDIAG is a program you run from the Windows search box on the task bar. After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.

Please attach here your Documents/Paradox Interactive/CK3/pdx_settings.txt .
From your Documents/Paradox Interactive/CK3/logs/ folder, attach here system.log , error.log  
27 days ago - AndrewT - Direct link
Windows 10 is not fully up to date, and the nVidia driver or card is having a problem too (as you might guess from that screenshot):
Windows Error Reporting:
+++ WER0 +++:
Fault bucket LKD_0x141_Tdr:6_IMAGE_nvlddmkm.sys, type 0
Event Name: LiveKernelEvent

First please run the Update app in Windows and apply the new Windows 10 version you will see there. Reboot, then run it again, apply everything it finds reboot - keep doing that until fully up to date.

Then do a clean reinstall of that driver:
- uninstall it and all other nVidia software
- reboot
- install it again by fresh download
Download Drivers | NVIDIA - reboot again

I hope that does it! Because if not you may have a hardware problem with that card, I'm afraid.