Halo Walkthrough: The Pillar of Autumn
I liked this level a lot. You wake up and find you're the only one who survived the landing. Grab all the stuff and run left across the bridge immediately. The bad guys are coming. Head straight and you'll find two buildings plus some guys. Stay with them and protect them as a few drop ships come down. Soon a warthog will be dropped for you and if you're lucky you'll get one or two guys to jump into it with you. Don't run them over!
Head forward down into the mouth of the cave. You go around little corridors, and at one point you have to rev up speed to jump over a chasm. Then you get to the light bridge - a huge unjumpable chasm. Drive your warthog over to the right. There's a passageway you have to walk up to get to the light bridge controls. Activate them, then go back down to the warthog and drive across.
Master Halo Walkthrough