Hello, Adi! It would be a good idea to try this first:
Method number 1
First, go into C: > Feralheart. If you look at the FH main folder, you will see a flie called:
'orge.cfg'
Click it, and open it with 'NOTEPAD'.
(http://i62BannedImageSite/28re5wn.png)
Look at the first two lines in the orge.cfg file. That is where you change your rendering system.
(http://i58BannedImageSite/vhfdop.png)
If you followed everything that was typed and the instructions in the pictures, you should have successfully switched your rendering system.
If that doesn't work for you, you can go into C: (local disk on PC) >>> Feralheart >> media > particles and delete any ending in _0, _1 and so on. You can also try running FH as an administrator. None of that works? Best bet would be to reinstall completely. Your game may be corrupted, etc. (Save all mods of value somewhere else before uninstallation!)