Halo: Combat Evolved/Halo

Flawless Cowboy
You awake, dizzy and disorientated, you have bodies all around your crash zone. All the other marines are dead, you are the sole survivor. Head outside the Escape Pod and pick up all the ammo and grenades on the ground. Cortana will tell you that a Covenant dropship is inbound and that you should take to hiding in the hills. Pass the ravine and continue on the path. On the easier difficulties, you could take out the Covenant that come in the Dropship and the two Banshees, but on more challenging modes like Legendary, just skip this. You should come to a wide opening where several Grunts and Elites are waiting for you. Take them out and jack their weapon. Be sure to pick up the Plasma Grenades while you're at it.

You should eventually come to an area where several Covenant are being dropped off by another Dropship. They start shooting opposite your direction. What could there be? Snipe some of the Grunts with your Pistol (to zoom, press in the thumbstick). Head down the path, and you should come across some Marines. Help them out and kill off the Covenant.

You will be told to standby and help the Marines kill the incoming Covenant forces as an EVAC arrives. Four more dropships should come. Take all the Covenant out and stock up on any human weapons you need by the lifeboat. Be sure to pick up the Covenant's weapons.

Eventually you will be flanked on both sides by Covenant, but on the easier settings you should have no problem at all. On Legendary, you should toss a Plasma Grenade at any Elites you see. Plasma Grenades stick to all targets (that means allies, too, so be careful). If you need some health, there is some by the same lifeboat you received your extra ammo from.

After you have successfully defended the Marines from all four Covenant dropships, a Pelican (UNSC dropship) will arrive with a Warthog. Warthogs are your basic human land vehicle which can hold a driver (obviously), a passenger, and a gunner who uses the turret to take out any enemies. Some marines will hop into the Warthog with you.

Once you're in, drive the Warthog down the path and into the cave below. Keep driving until you hit a dead end, then take a left turn and jump over the narrow gap onto the next landing. Be sure not to fall off, or you may possibly injure/kill your fellow Marines.