Cool idea. I would've liked there to be something more to being a ghost that just searching for a potion. Like maybe the reaper goes around trying to collect your soul. Or it's a race againt time to find a potion.
I also found the colliders a bit unforgiving. Such as the water killing me if my head touches it...even though technically my feet are the only thing on the floor and my head isnt touching the water. U could use two colliders, one thats just the feet and the other thats the entier body. (though idk what game engine u using sooo ye)
Other than that. Cool idea (noice)