Originally, Dungeons & Dragons was an evolution of the Chainmail medieval miniatures game, with the distinction that each player controlled a single figure and had a wider variety of actions available. The original D&D boxed set bore the subtitle, "Rules for Fantastic Miniature Wargames Campaigns Playable with Paper and Pencil and Miniature Figures". However, Dungeons & Dragons did not require miniatures, referring to them as "only aesthetically pleasing". Advanced Dungeons & Dragons likewise included a relatively short section describing miniature use, in conjunction with the official AD&D miniatures being produced at the time. As the game developed, miniatures became more of an optional add-on. The AD&D 2nd Edition accessory Player's Option: Combat & Tactics introduced a more elaborate grid-based combat system that emphasized the use of miniatures; a streamlined version of some of these concepts appeared in D&D 3rd edition. Although not strictly necessary, the 4th edition of the game assumes the use of miniatures, and many game mechanics refer explicitly to the combat grid. In addition to reducing ambiguity about the size and position of characters, this allows the game to specify rules for reach, threatened areas, and movement rates. The 5th edition de-emphasized these mechanics, and returned the use of miniatures to mostly optional.