Dungeons & Dragons 5th edition

Several different editions of the Dungeons & Dragons (D&D) fantasy role-playing game have been produced since 1974. The current publisher of D&D, Wizards of the Coast, produces new materials only for the most current edition of the game. Many D&D fans, however, continue to play older versions of the game and some third-party companies continue to publish materials compatible with these older editions.

After the original edition of D&D was introduced in 1974, the game was split into two branches in 1977: the rules-light system of Dungeons & Dragons and the more complex, rules-heavy system of Advanced Dungeons & Dragons (AD&D). The standard game was eventually expanded into a series of five box sets by the mid-1980s before being compiled and slightly revised in 1991 as the Dungeons & Dragons Rules Cyclopedia. Meanwhile, the 2nd edition of AD&D was published in 1989. In 2000, the 3rd edition, called simply Dungeons & Dragons, debuted. The 4th edition was published in 2008. The 5th edition was released in 2014.

Revised editions of the core rulebooks (compatible with 3rd Ed. via errata)

The original D&D was published as a box set in 1974 and featured only a handful of the elements for which the game is known today: just three character classes (fighting-man, magic-user, and cleric); four races (human, dwarf, elf, and hobbit); only a few monsters; only three alignments (lawful, neutral, and chaotic). The rules assumed that players owned and played the miniatures wargame Chainmail and used its measurement and combat systems. An optional combat system was included within the rules that later developed into the sole combat system of later versions of the game. In addition, the rules presumed 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, but the rules provided no overview of the game so it was difficult, without prior knowledge of tabletop wargaming, to see how it was all supposed to work. The release of the Greyhawk supplement removed the game's dependency on the Chainmail rules, 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).

...
Wikipedia