As for your question: To play as Admin: Right click the Feral Heart (application) and press "Run as Administrator".
(Some other suggestions if needed)
Go into C: >>> Feralheart >> media > particles and delete any ending in _0, _1, etc.
Change your rendering system in C: > Feralheart. Go to orge.cfg and replace the first line with either:
Render System=Direct3D9 Rendering Subsystem
[Direct3D9 Rendering Subsystem]
Or this:
Render System=OpenGL Rendering Subsystem
[OpenGL Rendering Subsystem]
It depends what rendering system you have. If you have the first one, change it to the second one. Vice versa.