A Monument To All Your Sins Achievement
A Monument To All Your Sins150
Completed every mission in Halo: Reach alone, on Legendary.
You must complete all 9 campaign missions on Legendary Difficulty.
Please refer to Gods Must Be Strong for more information and tips.
The missions you must complete are as follows:
- Winter Contingency
- ONI: Sword Base
- Tip of the Spear
- Long Night of Solace
- New Alexandria
- The Package
- The Pillar of Autumn
You do not need to do "Noble Actual", as it is only a cutscene, not a mission.