If you are trying to change your rendering subsystem through the in-game options, and it keep going back to the OpenGL or won't change, I would try changing it directly through the ogre.cfg file. To do this, go to your Feral Heart folder and find the ogre.cfg file. Right click on the file, open it with Notepad, and edit this part:
Render System=OpenGL Rendering Subsystem
[OpenGL Rendering Subsystem]
To:
Render System=Direct3D9 Rendering Subsystem
[Direct3D( Rendering Subsystem]
Be sure to save the edits you made and close the FH application if you have it open. When you start the game up again, there may be an option for you to choose the OpenGL or Direct3D9 option in a pop-up. You may not always get the pop-up, but select the Direct3D9 option if you do.
If this doesn't help the issue, do feel free to explain your problem a bit further so that we can understand your issue. c:
