D20 system

The d20 System is a role-playing game system published in 2000 by Wizards of the Coast originally developed for the third edition of Dungeons & Dragons. The system is named after the iconic 20-sided dice which are central to the core mechanics of many actions in the game.

Much of the d20 System was released as the System Reference Document (SRD) under the Open Game License (OGL) as Open Game Content (OGC), which allows commercial and non-commercial publishers to release modifications or supplements to the system without paying for the use of the system's associated intellectual property, which is owned by Wizards of the Coast.

The original impetus for the open licensing of the d20 System was the economics of producing roleplaying games. Game supplements suffered far more diminished sales over time than the core books required to play the game. Ryan Dancey, Dungeons and Dragons' brand manager at the time, directed the effort of licensing the new edition of Dungeons and Dragons through the 'd20 System Trademark', allowing other companies to support the d20 System under a common brand identity. This is distinct from the Open Game License, which simply allows any party to produce works composed or derivative of designated Open Game Content.

Ryan Dancey believed that the strength of Dungeons & Dragons was in its gaming community instead of its game system, which supported his belief in Skaff Elias's axiom known as the "Skaff Effect" which suggested that other companies only enhanced the success of the RPG market leader, which was now Wizards of the Coast. Dancey also theorized that the proliferation of game systems weakened the RPG industry, and these beliefs led to the idea to let other publishers create supplements for D&D. This led to a pair of licenses released by Wizards in 2000, prior to the release of third edition D&D: the Open Gaming License (OGL) made the D&D third-edition mechanics permanently open and available for use as a set of "system reference documents", while the d20 Trademark License built on this by letting publishers use Wizards' official "d20" mark to show that their products were compatible. Unlike the OGL, the d20 License was written so that it could be cancelled at some point in the future. Initially there was a boom in the RPG industry caused by the d20 license, with numerous companies producing their own d20 supplements. Some companies used the d20 system to try to boost the sales of their own proprietary systems, including Atlas Games and Chaosium, while many more publishers exclusively produced d20 content, including older companies such as Alderac Entertainment, Fantasy Flight Games, and White Wolf, and new companies like Goodman Games, Green Ronin, Mongoose Publishing, and Troll Lord Games. The success of the d20 license helped to launch the RPG PDF industry; there was a demand for d20 products and electronic delivery offered players a very quick and cheap way to distribute content.

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