Twilight has loomed for decades. Rumors of the coming sun run across the city's dark alleys and corrupted courtyards. Impromptu festivals catch like wildfire as the denizens of the dark city usher in the season of the sun. You have precious few nights of perpetual moonlight remaining to tighten your grip on the city's great districts before the moon sets – and once the sun rises, all of your deeds will come to light, and a new age will dawn on Hemloch.

In Hemloch, each player has access to his own deck of minions belonging to five different factions: The Courtesans, The Darkened, The Ghouls, The Alchemists, and The Geared. Each turn, players place these minions into one of four locations in the city. Minions grant the players special abilities on their own, but playing Minions of certain factions into certain cities grants the player additional abilities.

Players score points by acquiring Potions and Trinkets (which may also be used for additional abilities at the cost of points) and by placing Influence markers in the various Locations.