I had the same problem and it turned out I had an older ImpulseReactor.dll
Go to C:\Program Files\Stardock Games\Demigod\bin and find your ImpulseReactor.dll. Rename it to something like oldImpulseReactor.dll or just delete it. Then in Impulse right click on Demigod in your My Games tab and choose Verify Download. It might take a couple minutes but it will eventually pop up telling you need to download an update. You'll get a small download that will provide you with the correct DLL.
Hopefully this works for you, it worked for me.