The Player's Option: Combat & Tactics book is a compendium of upgrades and refinements for the combat system of AD&D. Combat & Tactics uses battle maps divided into 1-inch square grids for its movement grid. The Combat & Tactics rules alternate between two movement scales: in melee scale, the default scale for close range encounters, one square represents an area 5' per side, and in missile scale, suitable for outdoor and long-distance settings, one square equals an area 5 yards per side, and the Dungeon Master shifts between scales as the circumstances of an encounter change. The weapon proficiency rules have been changed so that player characters can use any weapon they want, if they pay one or more extra slots. The book breaks the combat round down into several multi-step phases, including initiative and actions.