Halo: Combat Evolved Anniversary is a 2011 first-person shooter video game developed by 343 Industries, Saber Interactive, and Certain Affinity, and published by Microsoft Game Studios for the Xbox 360 console. From Wikipedia
The introduction of the Flood and Master Chief's encounter with 343 Guilty Spark on the Halo ring mark significant developments in the series, aligning closely with the original game's lore.
