Halo is a science fiction first-person shooter video game franchise created by Bungie and now managed and developed by 343 Industries, a subsidiary of Microsoft Studios. The series centers on an interstellar war between humanity and a theocratic alliance of aliens known as the Covenant. The Covenant, led by their religious leaders called the Prophets, worship an ancient civilization known as the Forerunners, who perished in combat with the parasitic Flood. The central focus of the franchise builds off the experiences of Master Chief John-117, one of a group of supersoldiers codenamed Spartans, and his artificial intelligence (AI) companion, Cortana. Other characters, such as Noble Six from Halo: Reach, are also introduced in the series. The term "Halo" refers to the Halo Array: a group of immense, habitable, ring-shaped superweapons that were created by the Forerunners to destroy the Flood. The games in the series are critically acclaimed, with the original considered the Xbox's "killer app". This led to the term "Halo killer" being used to describe console games that aspire, or are considered, to be better than Halo. Fueled by the success of Halo 3, the fourth through sixth entries in the series were released on the Xbox 360. Halo 3: ODST was released on the Xbox 360 in 2009, and Halo: Reach in 2010. A prequel to the original trilogy, Halo: Combat Evolved Anniversary, was released on the Xbox 360 in 2011 to commemorate the 10th anniversary of the original game's launch. Halo 4, the first installment of the Reclaimer Saga, was released on the Xbox 360 in 2012. Halo 5: Guardians, the second installment of the Reclaimer Saga, was released for the Xbox One in 2015. The series has sold over 65 million copies worldwide, making it one of the best-selling video game franchises of all time.
One is a futuristic single player sci-fi adventure, the other is a multiplayer-only fps arcade-style team deathmatch deathmatch game.