Technically 10: 1. Arrival - Mostly Walktrough, some fighting. 2. Seirra 117 - Start the fight. 3. Crow's Nest - Defend the base, blow it up. 4. Tsavo Highway - Escape the base, reach Voi. 5. The Storm - Fight Wraiths, a Scarab, destroy the AA Gun. 6. Floodgate - Fight through the Flood, find Cortana. 7. The Ark - Istillation 00, a Scarab, take off to Truth. 8. The Covenant - Reach the Citadel, 2 Scarabs, kill Truth. 9. Cortana - Fight through the Flood, get Cortana, get out. 10. Halo - Fight the Flood, destroy the Halo, get off of it.