quit in order to work on Minecraft full-time as sales of the alpha version of the game expanded. Persson continued to update the game with releases distributed to users automatically. These updates included new items, new blocks, new mobs, survival mode, and changes to the game's behavior (e.g. how water flows). To back the development of Minecraft, Persson set up a video game company, Mojang, with the money earned from the game. Mojang co-founders included Jakob Porser, one of Persson's coworkers from King, and Carl Manneh, jAlbum's CEO. On 11 December 2010, Persson announced that Minecraft was entering its beta testing phase on 20 December 2010. He further stated that bug fixes and all updates leading up to and including the release would still be free. Over the course of the development, Mojang hired several new employees to work on the project. Mojang moved the game out of beta and released the full version on 18 November 2011. On 1 December 2011, Jens "Jeb" Bergensten took full creative control over Minecraft, replacing Persson as lead designer. On 28 February 2012, Mojang announced that they had hired the developers of the popular "Bukkit" developer API for Minecraft, to improve Minecraft support of server modifications. This acquisition also included Mojang apparently taking full ownership of the CraftBukkit server mod which enables the use of Bukkit, although the validity of this claim was questioned due to its status as an open-source project with many contributors, licensed under the GNU General Public License and Lesser General Public License. On 15 September 2014, Microsoft announced a $2.5 billion deal to buy Mojang, along with the ownership of the Minecraft intellectual property. The deal was suggested by Persson when he posted a tweet asking a corporation to buy his share of the game after receiving criticism for enforcing terms in the game's end user license agreement (EULA), which had been present in the EULA in the prior three years. According to Persson, Mojang CEO Carl Manneh received a call from a Microsoft executive shortly after the tweet, asking if Persson was serious about a deal. Mojang was also approached by other companies including Activision Blizzard and Electronic Arts. The deal with Microsoft was arbitrated on 6 November 2014 and led to Persson becoming one of Forbes "World's Billionaires". Since the first full release of Minecraft, dubbed the "Adventure Update", the game has been continuously updated with