This is a multi-objective linear infection game that's based off the Halo 2 campaign mission 'Gravemind.' You must chase Truth through High Charity and fight off his Covenant legions.
Phase 1: Starts off at the beginning of the level where you confront Truth and his guards. You must defend your position while Cortana hacks into the doors. Afterwards you move through the building and capture the stronghold in the next section.
Phase 2: Drop down the disabled lift and capture the oddball in the next large floral area. Long range engagements are dominant here.
Phase 3: Head into the next building and there is a moving King of the Hill that you must capture. The hill moves closer towards the enemies down a narrow bridge corridor which increases difficulty overtime.
Phase 4: Finally you reach Truth and you must kill him. Target Truth until his health bar hits 0 and then you win.