If your game can't be displayed because its default resolution is too high for your screen, you'll need a second monitor which supports a resolution Height greater than 768.
(Laptop users, this is how to attach a second monitor: http://www.idahoaudiovisual.com/projectors-faqs) Some desktop users may need to reboot their computers with their first monitor unplugged to change display to the new monitor.
You should now have your second monitor up and running. **IMPORTANT: do NOT change desktop resolutions or you may be greeted by the "Unsupported Resolution" error when you reboot!** Start your game; in this case, Darksiders. In the options menu, go to "Advanced Options". In this case, the uncommon resolution we're trying to switch to is 1366x768, change the resolution to one with a height of '768'. Height is the second number (example: 1024 x 768)
If required, save your changes. Exit your game. Laptop users: Use that handy function + monitor command to return to your laptop screen. Desktop users: Switch back to your first monitor like you did before. You may need to reboot your computer.
Open your game (Darksiders). Your screen may look a bit stretched, but we're about to fix that. Return to Options> Advanced Options. Your uncommon widescreen resolution (ex: 1366x768) should now be available.