Russian roulette is a game of chance in which one or more of the six chambers of a revolver are filled with cartridges, the chamber is rotated
at random, and the gun is fired. The shooter bets on whether the chamber which rotates
into place will be loaded. If it is, he loses not only his bet but his life. In the
case of a revolver with six chambers (revolvers with 5, 7, or 8 chambers are also
common), the shooter has a 1/6 chance of dying (ignoring the fact that the probability
of firing the round is always somewhat less than for a -shot revolver because the mass of the round in the cylinder
causes an imbalance, and the cylinder will tend to stop rotating with its heavy side
at or close to the bottom, while the firing pin is opposite the top chamber).

A modified version is considered by Blom et al. (1996) and Blom (1989). In this variant, the revolver is loaded with a single cartridge, and two duelists alternately
spin the chamber and fire at themselves until one is killed. In the case of a revolver
with six chambers (and again ignoring any imbalance in a real revolver), the probability
that the first duelist is killed is then 6/11.