Arkham Horror

Arkham Horror is an awesome board game that will consume your time, money and sanity. It is both played too frequently and not frequently enough, because contradictory states of being are just part of the insanity of such things.

There are several expansion and a few spin-off games:

Curse of the Dark Pharaoh

The King In Yellow

Dunwich Horror

Kingsport Horror

Innsmouth Horror

The Black Goat of the Woods

The Lurker at the Threshold

Miskatonic Horror