The game is a simulation of the bloodiest battle in the American Civil War. It was first published as a supplement to Command magazine Issue #22.
The game includes a 22" x 34" hex map of the area of Sharpsburg where the battle was fought, 283 counters, and 18 pages of rules, charts, and tables.
Game turns are sequential, with each player moving, firing artillery, and then having two rounds of combat, each in turn. Also provided are rules for solitaire play.
Victory is determined by victory points earned by the Union player for capturing and maintaining control of geographical objectives and Confederate unit losses. If the Confederate player can hold the Union to less than 25 points, they win. Victory conditions are slightly different for the Solitaire game.