I just love all of your idea. This kind of upgrade could make me like them more and give interest. I just feel that they are normal sims with weird skin tone.
And i have some idea too:
If your house have the hunted trait:
- Your sims could be awake by weird noise, voice and might end up scared.
- Your sims can try to talk to the ghost (basically speaking loudly in the house), it can be a nice talk or a angry/mean talk.
- Your sims could call a king of ghost hunter pnj to find a way to calm/protect the house from them (Like incense/ a kind of good luck charm) and find out which kind of ghost he/she is.
-There can be 3 types of ghost
- a good ghost who would be nice, help the house, have a good aura to relax sims. After the ghost hunter came you could just nicely ask the ghost to leave. This ghost is powerful. If you talk nicely to him he'll help you more and if you talk badly to him he'll deploy a sad aura in the house for a couple day.
- a evil ghost who would just scared sims (might scared them to death if they have low motives), have a evil aura that will make sims scared them/make them uncomfortable, break things, messed up with the light.This ghost is very powerful. To get rid of him you'll need a strong protecting object, he'll be still there but his manifestation would be rare and he can't scare sims to death anymore. If you talk nicely to him he'll mock your sims and if you talk badly to him he'll scared them more and will be more present for a couple day.
- a neutral ghost who could be good or bad, depending of his mood and how you talk to him. He can evolve into a nice or evil ghost or stay neutral. He is less powerful than the other, so you'll just need a simple incense to block him.