Vista.
That's the cause.
A while ago Google decided to disable all hardware acceleration for chrome on XP and vista. Since node webkit basically is chrome, it eventually was incorporated into node webkit.
The reason it works in preview is because there's a workaround where you start from a shortcut of the exe with the target having --ignore-gpu-blacklist added to it, which is what c2 does. Theoretically that flag should be able to be added to the node webkit manifest so you wouldn't have to start from a modified shortcut, but for some odd reason it doesn't work that way. So currently, your only option is to make sure the players start the game from a shortcut with that flag added to it.