Obsession
What do I need for the cooperative mode, and what changed in its rules?
The Characters expansion contains the complete cooperative game against the Sneyds, including its own rulebook. Choosing Standard or Extended Play is mandatory in cooperative play; the rulebook listed it as optional, which the designer called a mistake and moved to the mandatory section. Playing it solo needs no special rule: you run both families yourself. The hosting family keeps all favours from shared guests, and the Sneyd cards are for co-op only, not for the competitive prestige deck.