Level 1 - Reville
 Halo 1 Walkthrough - Level 1
Calibrate and reach the Bridge
Revielle is an aptly named chapter for the start of Halo. After a brief cutscene with Cortana talking to Captain Keyes, talking about how the Pillar of Autumn has just fled from the Planet of Reach, he instructs her to make all crew ready for battle. Most notable on the ship is the Master Chief, who is in cryosleep.
You first come to your senses when you are awoken from your cryostasis, with a single marine in front of you. You will be instructed to use the right analogue stick to look around. Once you've done this, the Marine will open your cryotube and let you out. A brief instruction on screen will show you that the left analogue stick strafes and the right analogue stick shifts the Chief's vision around.
After walking around the bay, you will be beckoned to go over to the Marine again, who will then calibrate your vision and ask if you want your pitch inverted or left how it is. After this, you will be instructed to stand in the same dock on the opposite side of the room to charge your shield. Your shield is charged after you stay out of danger for a few seconds. In Halo 1, it's important to note that you also have a health bar beneath your shield, so health packs are a must if you are low on shield and health. The general rule of thumb is to keep your health up as high as possible, otherwise you'll find yourself dead fairly quickly.
Once your visionary and defensive, there will be an announcement by the captain that the Chief needs to report to the bridge. When you leave with the Marine, things start to go bad. An explosion will stop you in your tracks and force you to take the left hand route, over a nearby pipe to make your way towards the bridge. It will be a run-of-the-mill follow-the-corridor style intro to a game. You will meet a few elites, but you can't do anything about those, what with the lack of a weapon n' all. After a few corridors, close calls and twists and turns, you will find the bridge and Captain Keyes.
 All Constructs & Cyborgs first
Escape the Pillar of Autumn
The first level, as you would assume, is going to be fairly straightforward for the most part. After a brief cutscene with the Captain, Cortana is given to the Chief. She's now stored in the Chief's helmet memory. You both have to get to the drop pods and escape the Pillar before the Covenant take it down.
From the bridge, you exit and take the left path. As soon as you see a couple of grunts, you will be given a pistol for the first time. Fire with the right trigger and take them out. You will soon find a group of marines who are trying to hold off some elites. Either help them or carry on. A lot of this level is very linear and corridor orientated. You will follow the corridors and access ways until you come to a viewing deck. If you look out into space, you can see Covenant weapons blasting the docked pods and loading bays. Things start to heat up as more covenant invade the ship. Elites and Grunts now appear together in the ship. Elites are the ring leaders and usually appear with a group of 2 or 3 grunts. The main difference being that Elites have shields and mostly carry Plasma Rifles. They're the leader of the pack and take more to take down.
After going through various accessways and burning corridors, you will come to an area where there is a set of stairs and lots of Covenant on the landing above you. Fight your way up and through until you come to the final access hatch of the level. You will know because it will be completely dark and Cortana will tell you that you need to be silent. You don't need to be stealthy, but when you come out the other side, you have the opportunity to take out a number of Grunt and Elite enemies with melee attacks to the back, saving you the firefight. Grabbing some grenades around the end of the level when you are prompted will help you through the rest. When you get to the last life pods, take out any enemies around them and make your way into them. A cutscene will trigger and you, Cortana and a couple of straggling soldiers will make your way to the Ring world...