Halo 4 is a 2012 first-person shooter video game developed by 343 Industries and published by Microsoft Studios for the Xbox 360 video game console. Halo 4's story follows a cybernetically enhanced human supersoldier, Master Chief, and his artificial intelligence construct Cortana, as they encounter unknown threats while exploring an ancient civilization's planet. The player assumes the role of Master Chief who battles against a new faction that splintered off from remnants of the Covenant, a former military alliance of alien races, and against mechanical warriors of the Forerunner empire known as the Prometheans. The game features a selection of weapons, enemies, and game modes not present in previous titles of the series. Development of Halo 4 began in 2009 and continued until September 2012. Halo 4 is 343 Industries' first original title within the Halo series—previously, development of the main series was undertaken by Bungie, the creator of the franchise. In the developmental process, 343 Industries decided to explore the Forerunner fiction within the Halo universe, leading the team to design a new setting, enemies, and main antagonist. Existing characters and assets received visual overhauls, recreated from the ground up, and motion capture was used for animation within cutscenes. A goal for Halo 4's story was to incorporate more human elements; to achieve this, the developers chose to delve more deeply into the relationship between the two protagonists, Master Chief and Cortana. Several external studios assisted 343 Industries with developing Halo 4, and over 350 people worked on the game in total. The game was officially announced at Electronic Entertainment Expo 2011 (E3) on June 6. Prior to launch, Microsoft stated that Halo 4 was the most expensive video game title the company had created so far. The game was marketed with promotional events and videos, including the creation of a live-action film, Halo 4: Forward Unto Dawn. Halo 4 grossed US$220 million on its launch day and $300 million in its opening week—a record for the franchise. More than one million people played Halo 4 on Xbox Live within the first 24 hours of its release. The game was met with positive reviews by professional critics and received multiple nominations and awards from the press. It was re-released as part of Halo: The Master Chief Collection for the Xbox One in 2014, and was followed by a sequel, Halo 5: Guardians, in 2015.