Update says it has a 64 bit version now. How do you launch it in GOG?

As usual. Then see in bottom-right screen, it will say you run the 64b version.

Hi wxrance.

Starting the game through GOG Galaxy will automatically launch the version that is compatible with your OS.
If you run a 64-bit OS it will launch the 64-bit version.
If you run a 32-bit OS it will launch the 32-bit version.
If you wish to launch a specific version, bypassing the automatic GOG Galaxy launch, then you can create a shortcut of either the "Grim Dawn.exe" located in the "Grim Dawn" folder, for the 32-bit version of the game,
or the "Grim Dawn.exe" located in the "Grim Dawn -> x64" folder path, for the 64-bit version of the game.
There is an option of adding a "Command Line Argument" by going to your GOG Galaxy library (if you use the GOG Galaxy desktop application)
-> clicking on the game
-> clicking on the "MORE" button
-> on the dropdown list clicking on the "Settings" button
-> checking the box of the "Custom settings" entry, under the "CONFIGURE GAME" section.
Unfortunately I do not know what the appropriate command would be, but you could seek help in the official Grim Dawn forum found here;
http://www.grimdawn.com/forums

Cheers.

excellent post - very informative and concise. highly recomended - thank you on behalf of all the other, eerm, idiots :p