The object of the game is for the player to reach the charmed circle at the top of the stair with his playing piece. Along the way, the player moves his piece through a cartoony haunted house and encounters various obstacles (usually caused by other places, such as being turned into a mouse). One interesting event that can happen in the game is when a Whammy ball (a metal ball) is dropped down the chimney; it can roll out onto the board from any one of four random places, causing events to happen which usually knocks one of the players' token back a bit.
A popular boardgame with an interesting theme, nice artwork, and a three-dimensional construction, Which Witch? was a popular game with kids of the early 1970's and was subsequently brought back out in various incarnations. It was released in Britain as either Haunted House or Ghost Castle, and in other countries as Kummituslinna (Finland), Szellemkastély (Hungary), Spookslot (the Netherlands), Brivido! (Italy), or Embrujada (Spain). In 1986 Milton Bradley released a reformatted version, The Real Ghostbusters Game, which featured the same play but new artwork devoted to the cartoon series.
Note: Two American versions exist, one with a folded board in a regularly-sized box, and another in a larger box with an unfolded board.