Here is a list of suggestions you should try/look into:
1.) Have you tried changing your rendering system?
Try changing your Rendering Subsystem by going to Local Disk (C:)\FeralHeart then open up the 'ogre.CFG' in Note pad or any other word document, then replace everything that's in there with this:
Render System=Direct3D9 Rendering Subsystem
[Direct3D9 Rendering Subsystem]
Allow NVPerfHUD=No
FSAA=0
Floating-point mode=Fastest
Full Screen=No
Rendering Device=Monitor-1-Intel(R) HD Graphics
Resource Creation Policy=Create on all devices
VSync=No
VSync Interval=1
Video Mode=1024 x 768 @ 32-bit colour
sRGB Gamma Conversion=No
[OpenGL Rendering Subsystem]
Colour Depth=32
Display Frequency=N/A
FSAA=0
Full Screen=No
RTT Preferred Mode=FBO
VSync=No
VSync Interval=1
Video Mode=800 x 600
sRGB Gamma Conversion=No
Then save and try again. If it doesn't take affect - restart your PC too.
2.) Go to (C:) Local Disk >>> FH folder >> media > particles
and delete all the files that have _0 or _1 or _2 at the end of them. (If you have recently exported a map, but keep in mind that this mightn't be correct. However if you have recently exported a map, then it is best to back up your files and re-install. Most of the time, that works.)
3.) Try opening the game up by right clicking the FH icon and 'Run as administrator'. That sometimes helps.
4.) Perhaps Reset your characters? I'm not sure if that will help.
I hope everything works out in the end. Good luck.