World of Warcraft was first announced by Blizzard at the ECTS trade show in September 2001. Development of the game took roughly 4–5 years, and included extensive testing. The 3-D graphics in WoW use elements of the proprietary graphics engine originally used in Warcraft III. The game was designed to be an open environment where players are allowed to do what they please. Quests are optional and were designed to help guide players, allow character development, and to spread characters across different zones to try to avoid what developers called 'player collision'. The game interface allows players to customize appearance and controls, and to install add-ons and other modifications.
World of Warcraft runs natively on both Macintosh and Windows platforms. Boxed copies of the game use a hybrid CD to install the game, eliminating the need for separate Mac and Windows retail products. The game allows all users to play together, regardless of their operating system. Although there is no official version for any other platform, support for World of Warcraft is present in Windows API implementations Wine and Cedega, allowing the game to be played under Linux and FreeBSD.