Specter Hunt

In Specter Hunt you have to pass as many rooms as possible. But be cautious, as there are ghosts hiding everywhere!

Two important informations are given to determine where they are hiding exactly:
First of all will ghosts only ever appear behind a corner.
The second informations comes from the symbols in each room. When hovering them with your cursor, they will mark certain tiles. Those marks are essential, because
if a potential hiding spot is marked by exactly two symbols, you will find a ghost
there for sure!

And shooting ghosts is satisfying. (And increases your score)

Can you determine all hiding spots before being killed?