So the game was working fine two days ago but today, with no changes to my system in intervening days, the game is crashing on startup.
On clicking play the cursor gets loading icon for a little while then it goes to a black screen for 5-6 seconds then drops back to windows.

Same problem.

If you guys are on Windows and you are using Galaxy, then have Galaxy repair/verify your files.

I repaired my files. I am getting the same issue - it is affecting all of my unity games that I know of - Shroud of the Avater, Kingmaker, Bards Tale Remastered. I click to open and then it crashes. A popup flashes for about 1/2 a second and then nothing happens. Bard's Tale Remastered at least captures the error.

I just spent a couple of hours on the phone with Dell Technical Support. They thought it was an issue related to the most recent windows update.

Reinstalling Kingmaker now.

Faulting application name: Kingmaker.exe, version: 2018.1.0.55711, time stamp: 0x5ae38dd2
Faulting module name: UnityPlayer.dll, version: 2018.1.0.55711, time stamp: 0x5ae38fac
Exception code: 0xc0000005
Fault offset: 0x00000000010c013e
Faulting process id: 0x658
Faulting application start time: 0x01d45e10330d4b4d
Faulting application path: C:\Program Files (x86)\GOG Galaxy\Games\Pathfinder Kingmaker\Kingmaker.exe
Faulting module path: C:\Program Files (x86)\GOG Galaxy\Games\Pathfinder Kingmaker\UnityPlayer.dll

Edit 10/07/2018 3:32 PM. Reinstalling the game did not help. :_(

Edit: Fixed on my end. This issue was a citrix update to my machine. This post explains what happened.
https://forum.unity.com/threads/unity-2018-2-7f1-windows-standalone-crash-on-first-run-unityplayer-dll-caused-an-access-violation.556585/

So it was an update issue, not windows update though.