I'd like them to have a single color instead of changing colors by moodlets (Don't know if we should have Death colors or select it ourselves), to have their original colors fading like in TS2 or Guidry from promos and when we aren't playing with them they need to stop breaking things automatically. Some new interactions and the ability to walk through solids would be awesome (Normal sims usually do this so I don't think it would be difficult lol). Maybe they could have a small perk tree to set them as sad, mischievous or vengeful ghost types.