Try exiting out of the Steam client, and starting the game directly from the '..\SteamApps\common\Divinity Original Sin 2\bin\EoCApp.exe' program file, by right clicking and running as administrator.
Try verifying local files: in the Steam library, right click on the game and select Properties, switch to the Local Files tab and then click on the 'Verify Integrity of Game Cache...' button.
With the GOG version, in the (optional) Galaxy client, select Divinity: Original Sin 2 in the left column, then click on the More button, and in the Manage menu select 'Verify / Repair'.
If you check the Event Viewer, does that give an error code or 'Faulting Module' file name that might help identify the cause of the crash?
- click Start (or WinKey-R), then type "event viewer" into the search box. in Windows 10, 'event' should bring up 'View event logs'.
- after starting the Event Viewer, expand 'Windows Logs' in the left column and select 'Application'
- in the center column, look for a recent error for the game (maybe sort by Date and Time, or search for 'EoCApp')
- check the information under the 'General' tab below the list of events, starting with "Faulting application name..."
Try browsing to the '..\Documents\Larian Studios' folder and delete the 'Divinity Original Sin 2' subfolder.
This folder contains the saved games, configuration files and a level cache folder. Normally I would suggest renaming the folder for troubleshooting purposes, but if you don't have any saved games that isn't an issue.
Next, extract the replacement folder from
this download into your '..\Documents\Larian Studios' folder, and see if that will let you start the game.
The graphicSettings.lsx file is set to 1280x720 Windowed mode, Very Low quality preset, which you can change in the options (manually, or hit autodetect) if this gets the game to start.
If the game still crashes, delete the downloaded My Documents D:OS 2 folder and try starting the game again. After that, please email supportdos2@larian.com with the report.zip file (or a Dropbox or Google drive link, etc) generated by the
D:OS 2 Analysis Tool, along with a description (or link to this topic).
Extract the zip file somewhere handy (like the Desktop) and in the AnalysisTool_DOS2 folder, run corresponding executable. It should detect the game install path, but if not you can browse to the 'Divinity Original Sin 2' folder. Optionally run the tests first, and then generate a report (it will be saved in the same location as the Analysis Tool).
The report will contain system and game information, and would contain your saves, if you were able to start the game to make any.
Also check the '..\Divinity Original Sin 2\bin' folder for any CrashDump files, and either add a few to the report.zip file, or zip them separately.