Set in the Lovecraftian universe, players are cultists, using rituals (tricks) to summon Elder Ones into the world.
After choosing the Elder One they wish to serve, they will perform rituals to call upon the Elder One. This is similar to a regular trick taking game. Here is what is different:
Players don’t win tricks, Elder Ones do;
Many rituals will be conducted at the same time;
Cards played trigger Elder Ones’ powers;
Some rituals can stop other rituals;
Players accumulate Madness Points for dastardly rituals;
Win condition:
The player who supports the Elder One with the most points is summoned into the world and wins.
If two Elder Ones tie, both players win.
Shoot the Moon: If a player supports no Elder Ones, they are considered the Investigator. If an Elder One gets no points then the Investigator is successful in stopping the cultists, and wins instead.
—description from the designer