Is that a day/night cycle I see? Because that's awesome. Perhaps you could give certain ghosts bonuses depending on the time of day? Or have some ghosts that can only be bound during daylight or during night. I know this is still in the very early stages; I'm just throwing a thought out there.
It looks quite nice so far though!
It's being invaded by the Othwerworld. Someone's nightmarish delusions come to life.