I celebrated the new year on a vacation with a group of friends. One of the best time-pass was the group game of Werewolf.
Be it a bus journey, waiting at a stop or a late night hangout on a beach, we played Werewolf everywhere. It required only some chits of paper (though we used a playing deck as a better substitute).
It requires minimum 7 players and is best experienced with 10-12 players.
I would highly recommend it to anyone who has a large group, scope to shout, and time to go through the rulebook.
----Update on April 2015----
I found the rules for another variation of this game: One Night Ultimate Werewolf.
Mirror of the above rule book.
I find this variation even better.