343 Guilty Spark
From Halopedia, the Halo wiki
343 Guilty Spark
343 Guilty Spark is an achievement in Halo: Combat Evolved Anniversary and Halo: The Master Chief Collection. It is awarded for completing the level 343 Guilty Spark on any difficulty.
In the original Halo: CE Anniversary it is represented by the Roman numeral of "VI" over a darkened version of Anniversary's logo and is worth 25 gamerpoints. In The Master Chief Collection it is represented by a screenshot of the swamp and is worth 10 gamerpoints.