This is a traditional , Bengali singing game which challenges teams of players to alter a popular song by either scale, rhythm or tone (depending on which music quality assigned to the team). The teams will take turns singing the variation they have quickly come up with, while the other teams try desperately to guess the original song.
In the experience of the informant, this game is played after celebrations. After the meal is finished, everyone will retire to a space more conducive to action, break up into three teams and the game will proceed. This takes place at any celebration, the most recent case the informant described was a one year old birthday party. There is no winner in this game, the point is not the competition, but simply to enjoy the musical challenge. Any popular Bengali song is fair game, the informant mentioned in particular a wealth of songs that have put the poems of Rabindranath Tagore to standard, popularly known melodies. The players of the game will then manipulate the melody, while still singing the same lyrics, the challenge for the guessers is then to identify original song by the lyrics disguised by an altered tune.
The informant described the significance of this game as a demonstration of the Bengali cultural obsession with music. The game assumes an incredible amount of musical skill, one must be able to identify and manipulate these separate qualities of music, and as a listener one must also have an incredible knowledge of Bengali music so as to be able to identify lyrics in isolation from their melodies. And because this game is so prevalent, it does indeed show an impeccable dedication by a very large group of people.
I believe such detailed interaction with music on such a large scale is very unique for a group of people. The expectation is more than just being able to play an instrument, to play from a sheet of notes, it is more that the music is internalized, personalized and improvised. Only a culture with the utmost respect and value would have such sacred personal involvement that would produce the playing of a game among so many people.
For another version that is more commonly played in other parts of India and Asia, Please visit this website: http://en.wikipedia.org/wiki/Antakshari