Source (Game engine)

Source is a 3D video game engine developed by Valve Corporation. It debuted as the successor to GoldSrc, with the first game being Counter-Strike: Source in June 2004, followed shortly by Half-Life 2 in November, and it has been in active development since. Source does not have a concise version numbering scheme; instead, it is designed in constant incremental updates.[1] Its successor, Source 2, was officially announced in March 2015, with the first game to use it being Dota 2, which was ported over from Source later that year.