People have be able to play on the beta releases of 10.12 before the name change, at least.
Are you shutting down all non-essential programs (especially anti-virus) before starting the game? GameCenter in particular caused a few conflicts with the El Capitan release, so try shutting that down (logging out).
Try verifying files:
In the Steam library, right click on Divinity Original Sin Enhanced Edition 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 Enhanced Edition in the left column, then click on the More button, and in the Manage menu select 'Verify / Repair'.
If you have the App Store relase, or GOG but are not using the Galaxy client, there is an alternate verification method.
Terminal
bash-3.2$ cd ~/Library/Application\ Support\ … up to the Divinity - Original Sin.app folder
bash-3.2$ codesign -vvv Divinity\ -\ Original\ Sin.app
This takes a while, and will output some lines starting with '--prepared' or '--validated'. If everything is fine, it will end with:
Divinity - Original Sin.app: valid on disk
Divinity - Original Sin.app: satisfies its Designated Requirement
After that, try running the game directly:
With the Steam version, in the client, right click on the EE in the library and select Properties, switch to the Local Files tab and click the 'Browse local Files...' button. After that, exit the Steam client and launch the game from Finder.
In the GOG Galaxy client, select the game in the left colum, click the More button and in 'Manage instalation' select 'Show folder'.
otherwise:
Terminal
bash-3.2$ cd ~/Library/Application\ Support\Steam\ … up to the Divinity - Original Sin.app folder
then
bash-3.2$ cd Divinity - Original Sin.app/Contents/MacOS
and there launch the executable
bash-3.2$ ./Divinity - Original Sin or something like that
If that doesn't help, please email supportdos@larian.com, with your system specs (use the 'System Report' button from the 'About This Mac' Apple menu item or the 'System Information' app in the utilities folder) and a Crash Report (collected in the 'Console' application).
