of the game, D&D Next was developed partly via a public open playtest. An early build of the new edition debuted at the 2012 Dungeons & Dragons Experience event to about 500 fans. Public playtesting began on 24 May 2012, with the final playtest packet released on 20 September 2013. The 5th edition's Basic Rules, a free PDF containing complete rules for play and a subset of the player and DM content from the core rulebooks, was released on 3 July 2014. In forty years the genre grew from a few hobbyists and boutique publishers to an economically significant part of the games industry. Grass-roots and small business involvement remains substantial while larger projects have attracted several million players worldwide. Toys industry leader Hasbro purchased Wizards of the Coast in 1999 for an estimated $325 million. Game systems The set of rules of a role-playing game is known as its game system; the rules themselves are known as game mechanics. Although there are game systems which are shared by many games, for example the d20 system, many games have their own, custom rules system. Game rules determine the success or failure of a character's actions, or adjudicate changes in the setting or in the characters themselves. Many game systems use weighted statistics and dice rolls or other random elements. Some systems are tied to the setting of the game they feature in, or to a broad genre such as science fiction, fantasy, or horror. Examples include Dungeons & Dragons itself (fantasy), Eclipse Phase (a specific science fiction setting), and Call of Cthulhu (settings where the Cthulhu Mythos features strongly). Universal role-playing game systems also exist, created with the intent of building a rule system that can be adapted to any genre. Examples include Basic Role-Playing, Champions, and GURPS. The d20 system, based on the third edition of Dungeons & Dragons, was used in many modern or science fiction game settings such as Spycraft and the Star Wars Roleplaying Game. In practice, most universal systems are more effective for particular settings, power levels, or types of play. Statistics Characters in role-playing games are usually represented by a number of statistics. Statistics are an abstract measure of how successful a character is likely to be at a class of tasks. Many game systems make distinctions between two key types of statistic: attributes and skills. Some, such as Burning Wheel and The Shadow