There a two factions in Secret Moon (three when played with the thief).
Minister and Guards: their goal is to either capture the princess or reveal both the princess and wanderer.
Princess, Wanderer and Priestess. They win if the minister is captured or if the princess and/or wanderer stay hidden until the end.
One match goes over three rounds, during each round the following actions are available:
Inspect: secretly look at another player's character card.
Inquire: ask "Who goes there?" to another player. This will give a clue about this player's identity. The princess and the wanderer will answer "..." when asked about their identity, while the priestess and guards will answer "It's just me." The minister answers "You fool! I'm the Minister!"
Accuse: guess a character card and reveal it (if incorrect, reveal your own). Note: when the guard is revealed, he's automatically captured.
Protect: defend someone or yourself (unavailable during round 3).
Disrupt: force another player to discard his/her turn (in exchange, you are captured).
Capture: "capture" a player with a revealed character (unavailable against guards).
Pass: choose a discarded turn order card and take it (for the next round).
Thief: The thief is an optional third faction. He tries to avoid being captured until the end. The Thief cannot protect himself nor can he use capture.
When inquired about his identity, he can choose to answer like the princess or the minister. The thief wins alone if he is not captured by the end of the game. For example: the princess gets captured, but the thief is still alive. The thief wins and is the only one to receive a victory point.