Basically, this is a lying game. The premise is that about there are werewolves in the village, so everybody must discuss who to kill. The problem is that the werewolves are pretending to be people and trying to get the villagers to kill one of their own. There are two teams: the werewolves, and the villagers. Most cards have a unique power and perform 'night' actions to gain information, which will help them figure out who is really telling the truth.
This is a relatively short game. If everybody knows how to play, depending on the rules set you can make each game take less than ten minutes. It's a game for three to ten players, and its a lot of universal fun. I've played with strangers and gotten to know them pretty well throughout the experience. When you meet somebody over a board game like Clue or Settlers of Catan, you don't really learn about them, but with One Night, since this is all about lying and picking out details about people, this is actually a great game to meet people with.
The gameplay is very simple. Everybody sits around a table, and selects a facedown card. Whichever card you pick is that role. If you pick a 'Villager' card, your goal is to figure out who the werewolves are. If you take a 'Werewolf' card, your job is to make everybody believe that you are a villager. Once everybody takes a card and knows their role, they set their cards in front of them on the table and close their eyes. One by one (or two by two, depending on the role) most people will wake up and take an action. Werewolves will know who the other werewolves are, the Seer can look at another player's card, the Troublemaker can swap two other players' cards, etc. There are about a dozen different roles with the base game, and most of them have something that they do when everybody else has their eyes closed.
Once the 'night' is over, everybody wakes up and discusses what happened. Anything goes. The only rule after that is at the end of an agreed upon time limit, everybody must vote who to kill, and majority rules. The thing about this is that everybody goes through a process realizing that anything goes. You can be told "Yeah, do whatever you want", but it doesn't sink in until somebody pretends to be the Seer when they are really the Villager. They don't need to be lying because they're on the good side, but you can. In fact, many times I have honestly told people that I am the Werewolf, because I'm usually bad at lying and honesty is way easier. There are reasons one would want people to think you're a Werewolf, which would make being honest like that fine, but I won't get into it here.
I actually really like lying board games. I've played Resistance and Good Cop, Bad Cop, and probably a few others, but this one has led to some of the best moments I have ever experienced when playing board games with friends. It's just a blast. The biggest problem I have with it, is that after varying amounts of time, people know how you lie. For some people it only takes one or two games. If you're lucky, it can take you dozens. But once you know how people act in certain scenarios (for example, knowing that I might very well be the Werewolf if I claim to be) then it makes it easy and thus, not fun. The best part of this game is the mystery of what you are told versus what actually happened so if you cheat or have personal experience in how people act in situations, it kills a lot of the joy of the game.
Still, I've played this game over a dozen times on more nights than I can even count. Playing with different groups of people helps a lot with the mystery, and its the sort of quick game that board game aficionados can always jump to as a fallback. Plus, expansion packs can add to how the possibilities and mystique of the game.