You start out in the cryo-freezing chamber. If you are playing easy you have to go through a number of tests which will affect the controller. I am not going to explain those so lets go on ahead:
- Follow the guy until he reaches the second door, it will explode killing him.
- Jump across the pipes in the middle of the hall by pressing A and come out the other side.
- Continue through doors passing by the chaos until you reach a marine
- Follow him until you reach the Bridge and Captain Keyes
- He will give you a pistol but it needs ammo so walk out until you reach some Grunts
- You will pick up ammo, so kill them.
- Walk ahead into a huge room the Cafeteria and help the marines fight off Grunts and Elites and try to save as many marines as possible. Go through a lot of rooms killing and blowing up Grunts and Elites.
- Keep going until you hear a marine yell: "What the ****, did something just hit us?"
- Stay away from the explosion that occurs behind two marines, then fight off all the guys, after that go inside the ship and take the overshield
- Keep on going until you hear Coratna say: "Covenant, on the landing above us"
- Defeat all the guys and go up on the ramps to continue on
- Keep going killing aliens until you hear Cortana say: "Theres one last lifeboat, get in, hurry!" or something like that and there you have it you beat the level...
If you want a detailed Guide for legendary mode click here