Battlestar Galactica is the newest in this style of game. I'm a huge fan of the television series so I was both excited and nervous about the game. Like video games, board game movie tie-ins generally don't turn out to be that good. Usually they are just a cash-in on the franchise. Early press made Battlestar Galactica sound like little more than Shadows Over Camelot with a science fiction twist. Thankfully it turned out to be much more!
(image courtesy @ henk.rolleman BGG)
Mechanically this sets the game up perfectly for a hidden traitor mechanic. At the start of the game everyone picks a character and is then dealt a loyalty card that says if you are human or Cylon. If you are human you want to get the fleet to Kobol; if you are Cylon you want to blow up Battlestar Galactica, overtake the ship or make the humans run out of resources. Only one side will come out victorious.
As a Cylon you generally want to keep your loyalty hidden as you can do a lot of damage that way. Each turn players draw a set of skill cards of five different possible colors, defined on their character sheet. Then they take a "good" action which might involve fighting Cylon ships, repairing Galactica or throwing someone in the brig. After that you are forced to resolve an event which is never good. These represent things like new Cylon ships appearing, prison riots, hostage negotiations and the like. At the bottom of the card are symbols showing if Cylon ships attack and if the battlestar spins up its faster-than-light (FTL) drives which is key to jumping closer to Kobol.
(image courtesy filwi @ BGG)
This part of the game really lets the hidden Cylons mess with the humans. Assuming everyone is loyal there should be a maximum of two bad cards in the stack if both random cards were bad. Everything else should be good. If not, you know someone intentionally played a bad skill card! As a Cylon you can try to toss in bad cards to push the event towards failure but you risk revealing yourself. While you don't know who threw in a specific card, process of elimination based on what color the card was and what skill cards each player draws can help narrow down the traitors. There's also the possibility for some bluffing and blame-laying; you can even toss in cards to try and frame someone else! The amount of mind-games and deduction is extremely fun and players are always interested as the totals are added up.
There's one more mechanic that makes Battlestar Galactica work. At the start of the game the loyalty deck is built with a specific number of human and Cylon cards based on the number of players. Only half of the deck is dealt out at the start, giving each player a single loyalty card. Roughly halfway through the game the second half of the deck is dealt, giving each player a second loyalty card. This means you may have been a loyal human at the start but you have now switched and become a Cylon! Players may have had everything figured out from the start but halfways through it can almost become a new game as the paranoia settles in all over again.
(image courtesy avyssaleos @ BGG)
For me, though, Battlestar Galactica is pretty much the ultimate competitive/cooperative game. It improves upon other games in the genre by adding in the second round of loyalty cards (allowing for changing loyalties) and players are involved every single round as they add cards to skill checks. I do think it runs a bit long and there are some minor balance issues but I've had a ton of fun every time I've played. It does a great job of invoking the feeling of the show and I think fans of the series will get into the game even more. Both sides of the game - human and Cylon - are engaging throughout the entire game, something other games in the genre struggle with. Assuming we have the time, Battlestar Galactica will always be my "traitor" game of choice.