 In June 2015 , Valve announced that the entirety of Dota 2 would be ported over to the Source 2 game engine in an update called Dota 2 Reborn . The beta was released to the public in June 2015 . On September 9 , 2015 , Reborn was officially released out of beta , which included a new user interface framework design , ability for custom game modes created by the community , and the full replacement of the original Source engine with Source 2 , making Dota 2 the first game to use it . Largely attributed to technical difficulties players experienced with the update , the global player base experienced a sharp drop of approximately sixteen percent the month following the release of Reborn . However , after various updates and patches , over a million concurrent players were playing again in January 2016 , with that being the largest amount of users since March 2015 . The move to Source 2 also allowed the use of the <unk> graphics <unk> , which was released as an opt @-@ in feature in May 2016 , becoming one of the first games to offer it . 
