Therules assume that players own and play the miniatures wargame Chainmail and use its measurement and combat systems. An optional combat system is included within the rules that later developed into the sole combat system of later versions of the game. In addition, the rules presume ownership of Outdoor Survival, a board game by then-unaffiliated company Avalon Hill for outdoor exploration and adventure. D&D was a radically new gaming concept at the time, and it was difficult for players without prior tabletop wargaming experience to grasp the vague rules. The release of the Greyhawk supplement removed the game's dependency on the Chainmail rules,[2] and made it much easier for new, non-wargaming players to grasp the concepts of play. It also inadvertently aided the growth of competing game publishers, since just about anyone who grasped the concepts behind the game could write smoother and easier-to-use rules systems and sell them to the growing D&D fanbase (Tunnels & Trolls being the first such).[3]
While AD&D was still in the works, TSR was approached by an outside writer and D&D enthusiast, John Eric Holmes, who offered to re-edit and rewrite the original rules into an introductory version of D&D.[7] Although TSR was focused on AD&D at the time, the project was seen as a profitable enterprise and a way to direct new players to anticipate the release of the AD&D game. It was published in July 1977 as the Basic Set, which included a single booklet covering character levels 1 through 3, and also includes dice and a beginner's module. The booklet collects and organizes the rules from the original D&D boxed set and Greyhawk supplement and features a blue cover with artwork by David C. Sutherland III. The "blue booklet" explains the game's concepts and method of play in terms that made it accessible to new players not familiar with tabletop miniatures wargaming. Unusual features of this version include an alignment system of five alignments[note 2] as opposed to the three or nine alignments of the other versions. This Basic Set was very popular and allowed many to discover and experience the D&D game for the first time. Although the Basic Set is not fully compatible with AD&D, as some rules were simplified to make the game easier for new players to learn, players were expected to continue play beyond third level by moving on to the AD&D version.[8]
This version was compiled and slightly revised by Aaron Allston in 1991 as the Rules Cyclopedia, a hardback book which includes all the sets except Immortals Rules (which was discontinued and replaced with the Wrath of the Immortals boxed set accessory). While the Rules Cyclopedia includes all information required to begin the game, a revised introductory boxed set, named The New Easy-to-Master Dungeons & Dragons Game (and nicknamed "the black box") was released at the same time.[10] A final repackaging of the introductory set, titled The Classic Dungeons & Dragons Game was released in 1994. By the end of 1995, TSR ended its support for the line.
In 1987, a small team of designers at TSR led by David "Zeb" Cook began work on the second edition of the AD&D game, which would be completed almost two years later.[11] In 1989, Advanced Dungeons & Dragons 2nd Edition was published, featuring new rules and character classes.[12]
The release of AD&D 2nd Edition corresponded with important policy changes at TSR. An effort was made to remove aspects of the game which had attracted negative publicity, most notably the removal of all mention of demons and devils, although these fiendish monsters were renamed tanar'ri and baatezu, respectively. Moving away from the moral ambiguity of the 1st edition AD&D, the TSR staff eliminated character classes and races like the assassin and the half-orc, and stressed heroic roleplaying and player teamwork. The target age of the game was also lowered, with most 2nd edition products being aimed primarily at teenagers.[14]
The game was again published as three core rulebooks which incorporated the expansions and revisions which had been published in various supplements over the previous decade. However, the Monster Manual was replaced by the Monstrous Compendium, a loose-leaf binder in which every monster is given a full page of information. It was the intention that packs of new monsters (often setting-specific) could be purchased and added to the binder without the expense or inconvenience of a separate book, allowing the book to be updated and customized as needed. This format proved highly susceptible to wear and tear, however, and presented difficulties in keeping alphabetic order when pages had been printed with monsters on each side. Subsequently, the loose leaf formatting was abandoned and the Compendium as a core book was replaced by single-volume hardcover Monstrous Manual in 1993, collecting popular monsters from the Compendium. The edition also greatly increases the power of dragons, in order to counter the impression of relative weakness of the game's titular monster.
Numerous mechanical changes were made to the game. The combat system was modified. The minimum number required to hit a target uses a mathematical formula in which the defender's armor class (AC) is subtracted from the attacker's THAC0 ("To Hit Armor Class '0'") number, a simplification of 1st edition's attack matrix tables that had appeared as an optional rule in the 1st edition DMG. Distances are based on in-game units (feet) rather than miniatures-board ones (inches). Critical hits are offered as optional rules.
Character creation is modified in many ways. Demi-human races are given higher level maximums to increase their long-term playability, though they are still restricted in terms of character class flexibility. Character classes are organized into four groups: warrior (fighter, paladin, ranger), wizard (mage, specialist wizard), priest (cleric, druid), and rogue (thief, bard). Assassins and monks were removed from the game as character classes, "magic-users" are renamed "mages", illusionists are made into a subtype of the wizard class, along with new classes specializing in the other schools of magic. Proficiencies are officially supported in the Player's Handbook and many supplements, rather than being an optional add-on. Psionics are no longer included in the Player's Handbook, though they later appeared in their own supplement.
Sales of Second Edition's core books were somewhat weaker than First Edition. Combined, the Player's Handbook and Dungeon Master's Guide sold over 400,000 copies in the first year of release, a solid hit, but their lifetime sales were not close to matching the huge success of First Edition.[15] The reasons why are contested. Michael Witwer, a biographer of Gary Gygax, cited the lack of involvement of Gygax and the changes that attempted to avoid controversy.[16] Ben Riggs writes that TSR insiders worried that the word "Advanced" in the title was scaring off interested newcomers into thinking the product was not for them, and more generally that players of First Edition could simply continue using their old books. Both Witwer and Riggs cite increasing competition from other role-playing games; First Edition was a trailblazer that had carved out an entirely new space, but many more tabletop role-playing games existed by 1989.[15][16]
In 1995, TSR re-released the core rulebooks for 2nd Edition with new covers, art, and page layouts.[17] These releases were followed shortly by a series of volumes labelled Player's Option, allowing for alternate rules systems and character options, as well as a Dungeon Master Option for high-level campaigns. They consist of:
Some of the optional rules include the introduction of a point-based system to allow players to pick and choose parts of classes to make their own class, and a more tactical combat system including attacks of opportunity.
The d20 System uses a more unified mechanic than earlier editions, resolving nearly all actions with a d20 die roll plus appropriate modifiers. Modifiers based on ability scores follow a standardized formula. Saving throws are reduced from five categories based on forms of attack to three based on type of defense. Skills and the new system of feats are introduced replacing non-weapon proficiencies, to allow players to further customize their characters. The combat system is greatly expanded, adopting into the core system most of the optional movement and combat system of the 2nd edition Players Option: Combat and Tactics book. Third edition combat allows for a grid system, encouraging highly tactical gameplay and facilitating the use of miniatures. 3rd edition removes previous editions' restrictions on class and race combinations that were intended to track the preferences of the race, and on the level advancement of non-human characters.[citation needed]
New character options include the new sorcerer class, the thief is renamed rogue (a term that 2nd edition uses to classify both the thief and bard classes), and the prestige classes are introduced, which characters can only enter at higher character levels and if they meet certain character-design prerequisites or fulfill certain in-game goals. Later products include additional and supplementary rules subsystems such as "epic-level" options for characters above 20th level, as well as a heavily revised treatment of psionics.[citation needed]
The d20 System is presented under the Open Game License, which makes it an open source system for which authors can write new games and game supplements without the need to develop a unique rules system and, more importantly, without the need for direct approval from Wizards of the Coast. This makes it easier to market D&D-compatible content under a broadly recognizable commercial license.[citation needed]
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