I can suggest any of these:
Solution 1 -
Go to Local Disk (C:) \\ FeralHeart \\ Media \\ Particles and delete anything ending in _0 _1 _2 etc. If you needed to do that, then I suggest re-launching FH again.
Suggestion already made above.
Solution 2 -
Go to Local Disk (C:) \\ FeralHeart and open the 'ogre.cfg' file in NotePad and replace everything in there with the following and save the changes after:
Render System=OpenGL Rendering Subsystem
[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=1280 x 800
sRGB Gamma Conversion=No
[Direct3D9 Rendering Subsystem]
Allow NVPerfHUD=No
FSAA=None
Floating-point mode=Fastest
Full Screen=No
VSync=No
Video Mode=800 x 600 @ 32-bit colour
sRGB Gamma Conversion=No
Or this, if the other is already in there:
Render System=Direct3D9 Rendering Subsystem
[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=1280 x 800
sRGB Gamma Conversion=No
[Direct3D9 Rendering Subsystem]
Allow NVPerfHUD=No
FSAA=None
Floating-point mode=Fastest
Full Screen=No
VSync=No
Video Mode=800 x 600 @ 32-bit colour
sRGB Gamma Conversion=No
Solution 3 -
Have you maybe updated your operating system? Example; upgraded from Windows 7 to Windows 8, or just updated your current operating systerm. Either way, it is possible that your game could be having compatibility issues. In this case, I suggest you change FeralHeart's compatibility to suit to what you are using.
1. Go to your desktop and right click the FeralHeart.exe Icon, then select 'Properties'.
(If it isn't on your Desktop, go to Local Disk (C:) \\ FeralHeart use the same method/instruction as shown below).
(http://i.imgur.com/RtPRfTB.png)
You should hopefully see this, or something similar depending on what operating system you are using.
(http://i.imgur.com/SEBKP2C.png)
2. Go to the 'Compatibility' tab and check the box for 'Run this program in compatibiliry mode for' in order to activate the dropdown box.
(http://i.imgur.com/VurPV6K.png)
3. As seen above, Windows XP (Service pack 3) is chosen for me by default. However, what you need to do is find the right compatibility that will run your game. Be sure to find the right compatibility for your operating system. If not, you should probably attempt to experiment a little with different configurations.
I'll be sure to come back with more if none of these work.