The premise is that about two dozen individuals meet at a large castle or house. Then on the first evening three or four are secretly selected to become the Traitors and the rest are classified as the Faithful.
Each evening the faithful try to banish a Traitor while the Traitors work together through the day and at banishment in an attempt to put them off the scent.
Then at midnight, the Traitors gather to 'murder' a Faithful. So each day two players are sent home. Occasionally there are no banishments or murders for various reasons.
One of those reasons is recruitment, as the Traitor number needs to be replenished if and when some are banished. So a Faithful can suddenly find themselves on the other side of the game, playing a very different role. Effectively one Faithful is lost.
The prize money grows each day as tasks are assigned for the whole group to work together and the better they do the more money they earn. At the end of the game, there can be no fewer than two players left but maybe one or two more. If any of the survivors are Traitors, they collect all the money, if there are only Faithfuls left, they divide the prize pot between them.
I've recently binge watched three UK series, two and a half US series and one Australian. The format is stuck to quite closely so there isn't a huge difference between them. Despite that, they have some differences. This is how I'd rate them.
Australia: The budget is more limited than the others. The facility used is more modest, they drive their own cars to assignments and the missions are not quite as elaborate. The people are of the everyday sort and they don't know each other. The responses of those who left the game were not given much or any airtime. The host does well enough but underplays his role. Rating 7/10.
USA: A bigger budget, a grand castle in Scotland and they are driven to assignments. What I think undermines it is using reality celebrities as contestants. They form into cliques and I don't think that is helpful in their traitor hunting. It could also be confused as a botox seminar.
The host is a Scotsman who pretends it is his castle they are using. His flamboyance is almost over the top but he does project a somewhat sinister indifference to those who depart, throwing their pictures on the ground dismissively. In season 3 a couple of contestants repeatedly used foul language. Rating 8/10.
UK: For me, this show has the best of both of the above. The contestants are everyday people although there is a celebrity show planned in 2025 along with a regular people one. The Scottish castle is used as with the US series. The host strikes a nice balance, sometimes cold and on other occasions a hint of warmth is manifest. Rating 9/10.
Summary: The show creates an environment where lying and deceit are essential qualities for the Traitors. The large pot at the end of the show is an incentive to do what is necessary to win. Those who talk too much usually draw unwanted attention to themselves and the better players are aware of that.
Once into a series, it's compelling viewing but the moral aspect of lying stops me from scoring any show ten. It surprised me that most contestants are accepting of being lied to. They presumably realise they would do the same if they were given the role of a Traitor.