From Halopedia, the Halo wiki
This is a walkthrough for the Halo 4 campaign level Requiem. It is written for play at the Legendary difficulty, but contains notes for lower difficulties. Like the previous level, you do not have any allies who accompany you. It is important to note that as this walkthrough at the Legendary difficulty, all strengths of enemies reflected are at the Legendary level.
Requiem (Rally Point Alpha)
Crashing within a Wreckage is my Job
Welcome to Requiem. Reload your assault rifle and your magnum. There are plenty of weapons for you to choose around the wreckage. Right in front of you, there are two dead Grunts, one of them with a Fuel Rod Gun. Inside a cylinder-shaped object, there is another dead Grunt with a Fuel Rod Gun. To your right, there is a weapon box with additional assault rifle and magnum ammo on the ground. The wreckage near that weapon box contains a dead Elite and a single SAW. In front of you to your left, the wreckage has a dying Elite General and two Battle Rifle-filled crates on what is left of the ceiling, the one of which is right next a Sniper Rifle. If you followed the path on the left, there is a dying Grunt. Further on, right before you enter the crevice, there are two Covenant carbines next to a Covenant terminal. Take what you need, and move on. Head through the cave, stare at the Forerunner spires in awe, and move on to the Warthogs. In far side of the wreckage, there is a weapon box with Battle rifles, Assault rifles, and Magnum. On Legendary, take the aforementioned SAW and a Battle Rifle. Get in a Warthog and start driving. If you are playing this level near midnight, feel free to get the Midnight Launch achievement.
After some driving, you will reach an open valley with three Phantoms. Park the Warthog near the canyon entrance's left wall, and take out your Battle Rifle. Aim for the two Grunts in the outpost closest to you, because as soon as they spot you, one of the Grunts will immediately head for the Ghost parked under the Sniper tower. Second priority should be the Elite, who will also head for the Ghost if it's close to the vehicle. Watch out for the Phantoms' fire as they fly over you. If one of the Covenant troops successfully got on the Ghost, get on the Warthog's turret and destroy it. Take out the Jackals last.
Head for the small encampment to the right, and kill the Sniper in the tower. Mop up the rest of the Grunts, but watch out for one of them, who is wielding a Fuel Rod Gun. There are three or so Grunts underneath the hill you are on, so take them out too. The last encampment consists of a single Elite with a Concussion rifle, a Jackal Sniper on the tower, several Grunts (one of them on a Plasma cannon), and a few Jackals. Slowly take them out with your Battle Rifle, since all of their weapons, except for the Plasma cannon, cannot reach you. If your Battle rifle runs out of ammo, there is Covenant supply case under the second encampment's sniper tower that contains Covenant Carbine for you to use. If you use them up too, to your left, under the hill, there is two supply cases, one of them with another four Carbines. Once you take all of them out from long range, move on. Since you haven't use any of your SAW's ammo, take it out, because there is a Zealot coming up. Since the Zealot is wielding a Concussion rifle, it wouldn't dare to use it in close range. Fortunately, the SAW is highly effective in close range. Stay close so you can hurt him, but far enough that he couldn't melee you. Move on into the cave, where there are three Grunts patrolling you. One of them wields a Fuel Rod Gun, so take it if your SAW ran out of ammo. If your SAW still has an extra magazine, keep the SAW.
No Beach Landing, No Desert, Just the Cartographer
After the going through the cave, you have reached the Gate. As you head closer to the structure, you will encounter an Elite with three Grunts. On Legendary, one of the Grunts will be wielding a Fuel Rod Gun, so you would want to take him out before the Elite, who you will deal with using the SAW or Fuel Rod Gun. On Legendary, numerous Grunts in this area will be wielding Fuel Rod Guns, so stay behind cover. In addition, the Kig-Yar Sniper on the structure will be wielding a Beam Rifle, so take him out after the first lance. Immediately on the right, there is a weapon box with Assault rifles and a single magnum on the ground. Take out the Elites, Grunts and Jackals at the bottom of the structure. Take out the Grunts and Jackals on the right side (you can take cover behind some rocks), and move on to the left side, where there are more Grunts and Jackals. When you are moving up the ramp that leads to the top, watch out for the camouflaged Elite Zealot. To avoid being surrounded, stay on the ramp, crouch down, and fire your weapons from there. Throw grenades if necessary, but save up your frag grenades. Pick up the Zealot's active camouflage, because it will be very useful in the up coming room. Restock the Fuel Rod Gun ammo.
Enter the cartographer. If your headshot-capable weapon is out of ammo by this point, move to the right wall in this room, and grab a Covenant Carbine from a Covenant supply case. Once you have collected all the weapons you need, activate the Cartographer.
The cartographer deactivated. That never happened before. That's too bad. Don't worry though, because we can fix this. Head to the right side first, activate the light bridge, and activate the core. After you activated the core, Covenant will enter the chamber. Stay on the core chamber's entrance, activate your active camouflage, and start sniping the Grunts, Jackals, and Elites. If your Carbine is out of ammo, move down the ramp and restock your ammo from a Carbine on the floor, next to a Covenant communication node. Feel free to take the last Elite head on once all the Covenant are dead. Activate the second core, and more Covenant will spawn into the chamber. Immediately, stick to the wall to your right. There is a Jackal Sniper on the raised platform on your right, so take him out first. Take out the Grunts and Jackals second. Head to the raised platform (where the Jackal Sniper was), and tackle the last two Elites. If you are running out of ammo for your Carbine, the supply cache mentioned earlier will provide you what you need. On Heroic (particularly with skulls activated), if you find this battle somewhat difficult, use the active camouflage, crouch, and sneak up on them. Once the last Elite is dead, Cortana will direct you to the Cartographer. Note that you can still activate the cartographer even when the Jackals and Grunts are alive.
A Star to Steer By (Rally Point Bravo)
This Bridge Looks Familiar...
Don't pick up the Hard light shield if you find it difficult to fight Elites. The active camouflage would be much more useful with its sneak attacks. Take out your Carbine and start sniping the Jackals and Grunts on the bridge below. Watch out for the Phantom, which will drop more troops and its side gunner will fire at you, even if you haven't gotten down on the bridge yet. Once most of the Covenant are dead, move down to the bridge. On the left side, there are two UNSC weapon crates: a box of Assault Rifles, and a box of Battle Rifles. You can keep your Carbine, or swap it for a Battle Rifle. If you are more comfortable with making headshots, feel free to take both the Carbine and battle rifle. If you have the Tilt Skull activated, take the Carbine instead.
Move on to the middle of the bridge. There is a Jackal Sniper next to the parked Banshee, so take him out first. After that, start taking out the Covenant on the floor below you. Feel free to harass them with your grenades. Move on, and at this point, another Phantom will arrive and drop off more troops. Banshees will also start attacking you. First, take out the Phantom's side gunner. Then quickly dispatch the approaching Grunts and Jackals. There are two UNSC crates here, but they don't contain anything. Instead, there are two human weapons next to them. A Rocket Launcher on the left, and a shotgun on the right. Take the rocket launcher and stay behind the rock. Wait for the Banshee to get close to you. Just like in Halo: Reach, the Rocket Launcher is capable of locking on to aircrafts. Once the Banshee is align with your reticule, fire your weapon. Once the Banshees are down, move on. The remaining Elite wields a Concussion rifle, so get close to him so he wouldn't fire it at point blank range. The next part only requires your Carbine/Battle Rifle, so go on as long as you have something with a headshot-capable weapon.
The Amount of Covenant Here is Too Damn High!
As soon as you enter the area, there is a Phantom. Fear not, as long as you remain at the entrance. Quickly take out the Grunts in front of you. On your left, there are more dropped human weapons: a box of Assault Rifles, a box of Battle Rifles, one Magnum, and Two SAWs. Watch out for the Shade turrets. If it isn't manned, keep watch for Grunts who will make a run for it. If there is someone on it, aim for their head, which is slightly above the turret's barrel. There are snipers on both side of the structure, so watch out. If the Ghosts haven't gotten to you yet after you took out the Shade turret, head to the side platforms, since you have more cover there. Take out the Covenant from here. Use the Plasma Cannon for Ghosts. After clearing the ground floor, take a Ghost and enter the structure. Since there is a pole blocking the ramp to the second floor, get off and melee one of the wings. As soon as it comes off, you can drive it up to the second floor (Note: This is not completely necessary if you are confident with just using firearms). Use the Ghost's boost to take out Elites, but don't slow down next to them, or they will board you. As you get to the third floor, a Phantom will enter the area and drop off Covenant. Stay behind cover until it flies away, or its gunners will kill you. If you didn't bring the Ghost with you, take the Jackal Sniper's dropped Beam Rifle and snipe the two Elites. Head to the top floor, where Sentinel Aggressors are fending off a pair of Hunters. There is a (Fuel Rod Gun-filled) Covenant supply case next to the ramps that leads to the top floor, so grab one before heading up. If you have trouble dodging a Hunter's Assault canon fire, stay on the ramp, so that when it fires its canon at you, the fuel rod would bounce off the floor. Use the Fuel Rod Gun and grenades to take them out. Once you're done, head on in to the Terminus. Congratulations, you just completed Requiem on Legendary.