From Halopedia, the Halo wiki
Sequence is a Canadian production studio located in Vancouver, British Columbia. They collaborated with 343 Industries to produce the graphics and audio for the terminals in Halo: Combat Evolved Anniversary, Halo 4, and Halo 2: Anniversary. They also produced the cutscenes for Halo: Spartan Assault. and Halo: Spartan Strike  The studio also produced the animated version of Halo: The Fall of Reach.