This is the classic party game "Telephone" (or "Chinese
Whispers") where instead of whispering the message to the
next player to keep others from hearing it, players say it in
different languages. Obviously, players must be
multilingual, and their languages must overlap such that
there can
be a chain of languages through the players.
For example, player one speaks English and Russian, player
two speaks Russian and Arabic, player three speaks Arabic,
Farsi, and Spanish, and player four speaks Spanish and
English. The message is translated from English to Russian,
then from Russian to Arabic, then from Arabic to Spanish,
and finally from Spanish back to English.
Actually, it would be better if all players speak some
common language (English in the example) in addition to
their individual languages, so that they can understand
how the message changes from beginning to end. You'd
still need whispering when the message's current language
is understood by players other than the one you're passing
it to.
To increase or decreaseI'm not surethe mutation rate,
allow discussion between each pair of players so that the
meaning of the message is passed more accurately. On one
hand, this reduces mutation by mishearing, but on the
other, I think it could encourage mutation through
interpretive translation.