It's an open secret that I like playing games with traitor mechanics, especially if I get to be the traitor. I'm a talented liar, but I only get to exercise the skill rarely, which is a shame because deception is a source of unbridled joy. For the uninitiated, traitor mechanics are those that allow a player to hide their allegiance, appearing to work with one group while advancing the agenda of another. Typically the traitors win conditions are the opposite of their apparent group's and the group gains some sort of bonus for correctly identifying them.
Fair warning: I'm going to talk about a few games and how well their traitor mechanics work and as I don't want to write several rulebooks out so I will engage in sweeping generalisations and simplifications. Don't treat this as a "how to play" guide.
Shadows over Camelot
My very first traitor game was shadows over camelot. In this game King Arthur's Knights of the Round Table (NO SINGING) quest to find Excalibur and the Holy Grail, defeat Lancelot and the dragon and generally advance the agenda of Camelot. Progress is measured in swords, as things go well the group gains white swords, if things go badly black swords are obtained, when the game ends the group wins if there are more white than black swords.
The game may have a single traitor, who wins if there are more black swords. If they are identified, the group gains white swords, but if they are not identified or if the group fails to identify them by the end of the game, white swords turn into black swords. Having a harsh penalty for incorrectly identifying the traitor is a common feature of traitor games and this implementation is particularly solid. In theory it would mean that the traitor needs to walk a fine line between doing things that sabotage the group and staying hidden enough to make the group guess wrongly.
In practice the limitations of the game let it down. There are a lot of things that rely on the integrity of the players, rules prohibiting players from communicating the contents of their hands are famously flawed and it's hard to say "I think we're bordering on cheating here" while you're the traitor. The game is also constructed so that the traitor will often be more successful if they are entirely open about their treachery, especially in smaller games. It's simply too hard to do things that sabotage the group without getting spotted, as most moves are performed openly. The bonus for being undetected is significant but does not outweigh and entire game of open sabotage.
I'm so pleased to have finally seen this series, so I don't have to worry about anyone spoiling that Adama turns out to be a cylon or similar. The game battlestar galactica does a fantastic job of capturing the paranoid feeling of the series and is clearly built entirely around the traitor mechanic. Again some players are working against the group and win if they lose. There's no specific reward for flushing them out and no specific benefit to them for not being caught, but whether they can continue their sabotage or not has a huge impact.
The sabotage mechanic is a significant improvement on Shadows over Camelot as it allows the traitors to cause significant problems while remaining undetected. Periodically players must play cards to reach a certain total, the cards are of five different colours and for any given check some colours add to the total and some subtract. Everyone throws their cards into a pot along with a couple of random cards and they're shuffled and revealed. This allows a traitor to throw in negative cards, without exposing themselves, as it is unknown who played which cards (or whether they came from the random pool). Over the course of the game players can build information, as only two cards are random a third negative card indicates a traitor was present and not every player will contribute to every pool. Whether the players identify and restrict the traitors before the situation becomes critical towards the end of the game has a huge impact on their success making engaging with the traitor mechanic rewarding for everyone playing.
This game isn't generally a traitor game, but it has one optional game mode in which a traitor is added. I feel that it deserves a special mention as the traitor is given a unique ability that I'd like to draw attention to: At any time the traitor can reveal their identity and select a player, if they can correctly name all cards in that player's hands they kill the player and can select another player to do the same with. This continues until they cannot name a player's hand.
One of the key elements of traitor games is that the traitor is present for all discussions of strategy and can make contributions that steer the players towards bad decisions. Flash Duel really pushes this element of the game, by forcing the players to deliberately withhold information from each other even if they are completely loyal. Given the small number of players and rapid play time I'm not sure I'd hold it up as a great example of a traitor game (though it is a great game in its own right) as for me the long con is a big part of the appeal of this sort of game. A big reveal at the end is nice, which can't happen if there's not been time for suspicions and tension to build.
To Make a Traitor Game
Pulling this stuff together, I think this is what you need to make a traitor game work:
The honest players must be encouraged to engage with the traitor mechanic, if identifying the traitor isn't important, the mechanic fails.
The traitor player(s) must be encouraged to engage with the traitor mechanic, if it's in their best interests to identify themselves and engage in open sabotage the mechanic fails.
If the mechanics of betrayal and deception can be creatively combined with other parts of the game this can enhance both aspects.
There are lots of bits and pieces beyond these three. It's desirable to create moments that people will remember at the end of the game when they talk about who was doing what and for what reason. It's also nice to design the game so that the traitor is not known with certainty until after the game, even if the players think they've identified and removed one, so there's always room for something to go wrong. I think those three things all need to exist to some extent for a traitor game to hold together well.
I've not got a traitor game on the back burner at the moment, but I guess it's something to consider. I considered adding one to Mage Academy, but couldn't think of a way to do it that wouldn't involve compromising the core gameplay for the regular version, so I figured it was better to do one thing well than two things badly. The important take away message for you, delicious friend, is that I can be trusted to look after your best interests. See you tomorrow.