This game simulates the raid by 617 squadron on the German industrial dams on the night of the 16/17th May 1943; the dam which used Barnes Wallis' 2bouncing Bomb". The game is a hex and counter wargame in the main, but involves three distinct parts. In the first, players form their crews and form 617 squadron. the second section uses die rolls to make sure that all crews are fit ton fly. the third part of the game is the simulation of the raid itself, with the allied players taking off from Britain at various intervals, and flying to and attacking the dams. They are hindered by a German player, who places anti-aircraft guns and uses cards to call up fighters to shoot down the allied planes. Combat (and bombing) in the game are both card-driven.