Girl Genius: The Works is a non-collectible card game that consists of several standalone decks of cards. You can play the game with any one of those decks, while also being able to combine some or all of those decks into a single deck for a longer game or a game with more players. Each deck contains many unique cards, but the gameplay is the same in all cases. Each player gets a five-card hand and twelve cards are laid out face-down in a patchwork pattern. Each card has colored symbols along each side, as well as a point value and special instructions. On your turn, you reveal one face-down card, then spin any face-up card 180º. After spinning, if any of the symbols on the edges of the spun card match the symbols on one or more of the surrounding cards, you "pop" the card(s) with the most matching symbols. "Popping" a card means that you must follow the instructions on the card (whether helpful or harmful), then (usually) add it to your score pile. Cards in your hand are used to replace any popped cards. The game is played until one player has 70/50/40/30 points with two/three/four/more than four players. The Castle Heterodyne deck includes themes and characters from Agatha's time in Castle Heterodyne, and her early days in Mechanicsburg. There are two major blocks of cards in this deck: Prisoners and Minions. Castle Heterodyne is a huge semi-conscious prison, and many of the characters in the story are stuck there. Thus, the Castle says, "If you have four Prisoners in your Score Pile right now, you win." But accumulating four of them can sometimes be pretty painful. Some of them mess up the board when you pop them, screwing up your plans. Others mess with your hand and Score Pile. The nine Minions in this deck have both good effects and bad, with other cards providing support for Minions.