I just figured out a makeshift way to make the 3D work properly with Nvidia 3D Vision. The 3D driver uses profiles for games to control how the 3D works, but Demigod doesn't have a profile as it's new. So, if you change the name of the Demigod.exe file to something that is actually has a profile, like Wow.exe for example, it will use the settings for that game. Using the WoW profile, the graphics do get rendered properly, although the interface still has some problems. You could try playing around with some other game profiles to find one that maybe works.
EDIT: After trying out a few profiles, I found one that is almost perfect: Spore. The interface remains a 2D image while the game itself is 3D, making it all work perfectly. The only problem is that since the cursor is part of the interface, when you're focused on the game you see a double image for the cursor. Otherwise, it's perfect. If you want to try it out, rename Demigod.exe to SporeApp.exe.
Unreal Tournament 3, UT3.exe, works just as well; maybe even better than Spore. If you can find one that fixes the cursor problem too, post it here. I know WoW fixes it by keeping it 2D when hovering over the interface and changing it to 3D when hovering over the game, but it requires you to disable the "Enable Hardware Cursor" option to do so. Demigod doesn't have this option, which is why it doesn't work.