For 16 to 20 players there are typically 3 Murderer, 2 Inspectors and 11 - 15 Civilians
Optionally the Moderator may also deal one of the Red Mood cards to each player, these suggest a way in which the players should behave during the game.
The game starts during the day with the players discussing who the Murderer(s) might be, to try to select them from amongst their circle of friends. A time for accusations to fly and fierce denials to be heard. At some point the Moderator must call for nominations and votes and eventually the player believed as a Murderer is convicted, that person then reveals their card and leaves the circle. Have the players guessed right or has another innocent Civilian been convicted!
At this stage of the game the discussion is likely to go on for some time so the Moderator might wish to give a set time and then signal that a decision needs to be forthcoming or nighttime will arrive with the inevitable Murder!
Night falls and the Moderator asks all of the players to close their eyes. He or she then calls for the Murderer(s) to open their eyes, the Murderer(s) select a victim, someone who won't wake up in the morning. The Murderer(s) then close their eyes.
The Detective(s) then opens their eyes and points out one of the players, the Moderator indicates with a thumbs down if that player is not a Murderer or a thumbs up if they are, the Detective then closes their eyes.
The Moderator now calls for everyone to open their eyes and the victim of the Murderer(s) learns their fate, reveals their card and leaves the circle.
Now it is daytime again and the cycle repeats, another potential Murderer has to be identified.
The Murderer(s) try to identify and kill the Detective(s), the Detective(s) tries to identify the Murderer(s) and get them convicted without drawing attention to themselves. You can be sure the Detective(s) will die if the Murderer(s) know who they are.
The Murderer(s) win if they equal or outnumber the Civilians so the Civilians need to be sure to identify them using any means possible.
The Hooks
Very simple to play and can be played in many environments with groups of all ages.
Can turn into a very theatrical experience with people becoming animated as they try to find the guilty.
Conclusion
A great party game, suitable for the whole family in many environments. Great with larger groups who don't game regularly. The cards are of good quality and they come in a neat plastic case which also contains the rules.
if you are playing with younger children then it is probably best not to use the Red Mood cards but with adults it's a good way of getting people to try to alter their natural personalities and get them immersed in the game.
Additional Reviews
Details from Boardgamegeek