World of Warplanes is a free-to-play flight combat massively multiplayer online (MMO) action game developed by Persha Studia in Ukraine and published by Wargaming in Belarus, set in the Golden Age of military aviation. The game was released on November 12, 2013 in CIS countries, and on November 13, 2013 in North America and in Europe. Wargaming's plan to develop a flight combat MMO action game was first conceived during the early stages of World of Tanks’ development. World of Warplanes was announced at E3 in 2011, less than two months after the World of Tanks release in Europe and North America. Development was assigned to Persha Studia, the Kiev-based development center of Wargaming. The game went from concept to a playable prototype in only two months. Early alpha testing began August 2011. Wargaming showcased the first public World of Warplanes trailer at Gamescom in August 2011. Wargaming first showed a closed demonstration of the alpha version to journalists at the Igromir Expo in October 2011. American aircraft were the first planes to be added to the World of Warplanes tech tree. On April 4, 2013, the non-disclosure agreement was lifted for the beta test players, allowing beta testers to share their thoughts, screenshots, and in-game videos. At that time, the game offered six battle arenas and over 80 aircraft models from USSR, USA, Germany, and Japan. World of Warplanes’ open beta testing started on July 2, 2013.