Sierra 117

Were you looking for Spartan John-117, also known as the Master Chief?

Sierra 117 is the second Campaign level of Halo 3. It is the first level to feature real game play, as opposed to the first level, Arrival, which is merely a cutscene and tutorial. Also, take note that this is the First Level that features messages from Cortana on certain occasions (moments).

Upon completing it on the Normal, Heroic, or Legendary difficulties, the player will earn the "Landfall" achievement and 20 Gamer points. Upon earning 15,000 points in FFA Meta scoring, the player will be awarded with the Guerilla achievement and 10 gamer points.

Setting
This level takes place in an African jungle that lies on the southern slopes of Shira peak, as confirmed via the hexadecimal code of the Halo 3 Beta and physically confirmed in the Halo 3 E3 2007 Trailer and the short video subsequent Bungie Podcasts (Mawenzi peak can be seen slightly obscured to the right of Uhuru peak, both which are part of the Kilimanjaro mountain.) The jungle is home to a Covenant Loyalist encampment, and hosts lush verdant forestry, rivers, rocky landscapes, waterfalls, and tunnels. It has been compared to "Off the Rock, Through the Bush, Nothing but Jackal" of Halo 2's Delta Halo, although it isn't the same place, because Sierra 117 is on Earth and Delta Halo is the same as Installation 05.

Plot
Having been found by Johnson and the Arbiter, the Master Chief is escorted through the jungle. Johnson has with him two squads of marines but after spotting a Covenant Phantom overhead, he decides to split them into two teams to try and reach an evacuation point at the river. The Master Chief, the Arbiter and one squad head one way, following the stream, while Johnson and the other UNSC forces scale a waterfall and head another way.

The Chief encounters the previously patrolling Phantoms, which drop off Brutes and Grunts. They also have to face Carbine-wielding and Sniper Jackals. Around the time they finish mopping up the first group of Covenant, they receive notice from Johnson that they cannot get into contact with another marine team, Bravo. Almost immediately after, the group comes across a stricken Marine held captive by a Brute on a log above them. The Brute beats the Marine, inquiring about an "Ark". After killing the Brute who was torturing the marine, they are told the rest of Bravo is dead, apparently pinned down by a Phantom and killed by a Brute Chieftain. The Bravo team survivor, Gunnery Sergeant Reynolds, then joins their cause.

Later on, UNSC forces and the Arbiter make it to the river for evacuation, but the Pelicans at the evacuation point are already under attack by Covenant infantry. Johnson is seen firing from the back of one of the Pelicans with a Machine Gun Turret and with combined fire, the Covenant are momentarily pushed back. However, before the Chief and Arbiter can reach them, Banshees show up and fire on the Pelicans with their Fuel Rod Cannons. Heavily damaged, they make a fiery exit out of the Chief's sight and more Brute and Grunt reinforcements show up to mop up survivors. After pushing through the Covenant forces, the Chief and the Arbiter are told over the COM that Johnson's Pelican has crash landed and shortly afterwards come across him and his squad fleeing from the crash site, pursued by Brutes and Grunts. The Chieftain mentioned earlier pulls his own Phantom out of the fight to regroup.

They desperately try and catch up with Johnson, killing dozens of Grunts, many Brutes and a handful of Jackal Snipers that were crowded around the area. After coming across the crashed Pelican, they find Sniper Rifles and Battle Rifles and they discover over the Pelican's radio that there is no sign of the second Pelican. It is assumed to have crashed and sunk into the lake. Master Chief, Arbiter and the surviving marines then find themselves in a thick jungle and have to fight past Jackals hiding in the trees and on the ground, with no sign of Johnson or his squad of marines.

They then reach a large dam where they see Johnson being taunted and kicked into a small building and held captive by a Brute Chieftain. It is implied this is the same Chieftain that killed Bravos men and pursued Johnson from his crash site. The area is also littered with Grunts and Jackals as well as half a dozen Brutes. With slow progress, the two heroes manage to fight their way through and around the dam and eventually take down the Brute Chieftain. They then rescue Johnson and the three surviving marines from his squad.

Johnson calls in Pelican Kilo 023 piloted by Hocus to come and pick them up, but are first engaged by two Phantoms which drop off hordes of Grunts and a few Brute Captains wielding Brute Shots. Whilst the group engages and kills the ground forces, the Pelican arrives and takes down the two Phantoms with missiles. Hocus then lands and evacuates the survivors and Johnson is seen patting the Chief on the shoulder in thanks before the Pelican flies off.

Walk It Off
Brutes on the prowl.

{Gameplay}

Sergeant Johnson: "First Squad, you're my scouts. Move out! Quiet as you can."

Co-op change: Johnson: "First Squad, you're my scouts. Arbiter, watch the Chief's back. Move out! Quiet as you can."

(3-4 Players Co-op) First squad you're my scouts. As for you, just try not to wreck my planet. Move out quiet as you can.

If the Chief waits and hangs around.

Sergeant Johnson: "Let's get moving, Chief. Come on. I'll lead you out."

Sergeant Johnson: "Bravo Team, this is Johnson. We got him. Fall back to the extraction point. Over."

Sergeant Reynolds {COM}: "Roger that. Reynolds out."

A Brute howls off in the distance.

Marine: "That sounded close."

Marine: "Yeah, too close."

Sergeant Reynolds {COM}: "Johnson, you be advised. Hostiles are -{static}- on the move -{static}-. I've got eyes on a -{static}- Brute Pack -{static}-. Over."

Segeant Johnson: "Say again, Gunny? You're breaking up." There is the ominous whisper of gravitational drives as a Phantom flies overhead above the trees.

Marine''{Whisper}: "Sergeant Major, Phantom inbound."

Sergeant Johnson: "We stick together, we're gonna get spotted. We'll split up, and meet back at the LZ. Chief, go with the Arbiter, head toward the river. Second Squad, you're with me."

Co-op change: Sergeant Johnson: "Chief, you and the Arbiter head toward the river."

''Johnson and Second Squad climb up the cliff by the water fall. The Master Chief and Arbiter lead First Squad. The Arbiter leads the Chief up on some rocks around a pile of fallen logs, while First Squad waits to go straight over, pointing out a Brute Captain Major.''

Brute Captain: "Spread out, you whelps! Find them!"

Marine(Whisper): "Up ahead! Single Brute, plus backup!"

Marine: "He's got power armor Chief!"

''First Squad engages the Brute and his Grunt subordinates along with the Master Chief and the Arbiter, taking them by surprise. They regroup.''

Arbiter: (To the Brute corpse): "The Prophets are liars, but you are fools to do their bidding!"

''A couple of Phantoms draw near, each deploying a squad of Grunts and Brutes, blocking the advance of the Master Chief and his allies. Eventually, they are cleared, and the Marines form up at a winking flare at an underground cave.''

Male Marine/Female Marine: "Those Brutes are tough. Grunts ain't no slouches either."

Arbiter: "The Grunts' new-found courage is but fear. When we are victorious, all who serve the Prophets will be punished."

Reply in Co-op: Female Marine or Male Marine : "Maybe the Brutes put something in their tanks."

''After advancing through the caves, a massive forested expanse is found: the "Grunt Camp". Sleeping Grunts litter the first half while a few Brutes, Jackals, and other Grunts patrol the far hills.''

Marine: "Sleepers! Take 'em out, nice and quiet! {On Heroic and Legendary} Jackals, on the ridge! Stay low; looks like they've got Carbines."

After the team clears the Covenant Camp.

Sergeant Johnson {COM}: "Pelicans are en route, Chief, but I can't reach Bravo. If you find 'em, get 'em to the extraction point."

Beyond the encampment, a Brute Captain is torturing a Marine Sergeant on a log {It is possible and optional to save the Marine by killing the Brute}.

Brute Captain: "Tell me its location!"

Sergeant Reynolds: "Kiss...my...ass."

''If the Sergeant is not saved, the Brute Captain breaks his' spine and throws him down, noticing the Master Chief and Arbiter. If he is saved, Reynolds jumps down from the log, grabbing a nearby fallen Assault Rifle and joining the Master Chief and the Arbiter in their fight.''

Sergeant Reynolds: "Brute Chieftain. Phantom. Pinned us down... killed my men."

First Squad continues on until they reach another cave.

Arbiter: "The river. Hurry!"

''The minor UNSC force continues forward, towards further caves and pushing towards the river, where Johnson has established an extraction point for Second Squad. They head down a steep slope for some underground caves that lead to the river.''

Cortana {Cortana Moment}: "Could you sacrifice me to complete your mission? Could you watch me die?"

Marine: "Sir, you okay?"

Marine: "Your vitals just pinged KIA."

Charlie Foxtrot
Hostile air inbound.

''Second Squad leaves the caves; the river is around the next bend. Three Marine corpses are scattered on the ground, with BR55HB SR Battle Rifle ammunition and Fragmentation Grenades.''

Sergeant Johnson {COM}: "Chief, Pelicans are at the river. We've got company, so hustle up!"

Arbiter: "Grenades! Blow them to bits!"

''Beyond the steep slope is a river substation, next to a raging river. A pair of Pelican drop ships, hover above the river, and their door gunners fire on a cluster of Covenant troops that have tunneled themselves in the substation. They are the extraction force to evacuate the Master Chief and his team.''

Female Pelican Pilot {COM}: "Hold on. Got a contact."

As the Master Chief and his allies clear the site of Covenant that is nearer to the Pelicans in the substation, two Banshees streak in along the river.

Female Pelican Pilot {COM}: "Banshees! Fast approach!!"

Echo 51 {COM}: "Break off- NOW!"

The Banshees launch a high-speed strafing run against the Pelicans, and explosions cascade over them as the Pelicans rock.

Echo 51 {COM}: "Watch yourself!"

Female Pelican Pilot {COM}: "I'm hit! I'm hit! AAAHHHH!"

Echo 51 {COM}: "Lost a thruster. Hang on!"

Sergeant Johnson {COM}: "Get a hold of her!

Echo 51 {COM}: "Negative! We're going down!"

''Both Pelicans streak away around the river bend. The first Pelican plunges into the river beyond the dam, but the second, Echo 51 loses control, plowing into the top of the cliff and drops down. While Master Chief, the Arbiter, and the Marines fight through to secure the substation despite two waves of Brute-led Covenant Loyalist reinforcements, Johnson and his team leave the wreck of Echo 51 but are beset by a Brute ambush .''

Arbiter/Marine{Co-op only}: "The Banshees will return. Back into the jungle, hurry."

Sergeant Johnson {COM}: "Chief, can you hear me..{static}. My bird's down. Half a click -{static}- downstream from your position."

If on Easy or Normal


 * Marine: "Jackals. On the ridge. Stay low. Looks like they got Carbines."

''After the Chief and the Arbiter pass through the short Jackal Sniper-laden gorge "Sniper Alley", they see a bridge. Three Marines are crossing it, under heavy fire, retreating from Echo 51's crashed Pelican. They hear a familiar voice over the COM unit as a Brute leads a charge against the fleeing Marines.''

Sergeant Johnson {COM}: "Come on, you dumb apes! You want breakfast? You gotta catch it!"

Johnson and some of the Marines frag the Brute and his fellow soldiers on the bridge, and run off into a cave.

''The Chief and Arbiter encounter many hostiles, including a Brute Chieftain on the side of a Phantom, who flies off when either his gunner, or much of his troops are eliminated. The Chief and Arbiter secure the area, and discover Echo 51's crash site by the riverside: the Pelican flipped over after hitting the cliff, scattering ammunition and weapon racks in the area, including a SRS99D-S2 AM Sniper Rifle and other munitions. Echo 51's radio is still operational, however.''

If the Chief or the Arbiter waits by Echo 51's radio.

Crow's Nest Controller: {Echo 51's Radio}: "Echo Five-One, this is Crow's Nest. Echo Five-One, please respond! {Pause} Hocus, Five-One is down, divert for emergency evac. Over."

If any of Echo 51's Marines are still alive

Arbiter: "Again, the Brutes show their weakness."

If any Marines accompany the Chief and the Arbiter.


 * Marine: "Sergeant Major went this way, Chief. Through the cave."

''The Master Chief leads the Arbiter (and any accompanying Marines) through the caves towards where Johnson is being held".

Quid Pro Quo
Rescue at the dam.

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{Cutscene}

''At the end, the Master Chief and Arbiter reach a low cliff, viewing a Loyalist-held dam. The Arbiter spots the Chieftain beating Johnson on the far left in front of a small building.''

Arbiter: "See how they bait their trap?"

''The Chieftain roars at Johnson. Johnson punches the Chieftain in the stomache with no effect.''

Arbiter: "I will help you spring it."

''The Chieftain growls loudly and kicks him back inside the "prison".

{Game play}

''The Chief and Arbiter battle their way across the dam, taking down the Chieftain. They finally reach Johnson, who's been tied up and imprisoned behind a plasma shield.''

Sergeant Johnson: "This isn't as fun as it looks. Cut the power!"

If no Marines came with the Chief or the Arbiter or already died, the other three Marines in the prison will be still alive and await rescue.

Marine Escapee: "Brutes were gonna gut us, sir."

The Master Chief releases the plasma shield that was imprisoning Johnson and his fellow Marines.

Sergeant Johnson: "We're even, as long as we're only counting today. Kilo 23, what's your ETA?"

Hocus {COM}: "Imminent, Sergeant. Find some cover. Gotta clear a path."

Sergeant Johnson and the Marines grab Covenant weaponry from nearby crates.

Sergeant Johnson: "Roger that, Hocus. Friendly gunship, coming in hot!"

''Two Phantoms arrive, carrying reinforcements. The Chief, Arbiter, Johnson and any accompanying Marines hold position under the "Prison" for shelter until Kilo 23 arrives.''

Sergeant Johnson: "Hocus! Phantom!"

Hocus {COM}: "I see 'em! Standby. Going loud. Everyone down!"

''The Pelican Dropship Kilo 23 rounds the river bend, directly in front of the two hovering Phantoms. Hocus, Kilo 23's pilot, lets loose a missile barrage, etching the air with vapor contrails as the first Phantom explodes in a brilliant coruscation of light.''

Hocus {COM}: "Scratch one Phantom!"

''If any ground forces remain, Kilo 23 will take them out. Kilo 23 fires two missile barrages at the second Phantom, and sends it plunging into the river.''

Hocus {COM}: "Scratch two!"

''Hocus lowers the Pelican to the dam for pickup. Johnson, the Master Chief, the Arbiter and any remaining Marines board Kilo 23.''

Sergeant Johnson: {If the Chief doesn't board the Pelican} "Come on Chief! The world won't save itself!"

If the Chief stills doesn't board.

Sergeant Johnson: "Are you or are you not going to finish the fight?"

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{Cutscene}

''Kilo 23 takes off. Johnson gives the Chief a pat on the shoulder and goes into the cockpit. Kilo 23 shuts the back hatch and flies over the first dam, en route to Crow's Nest. The view cuts to an area in the jungle. Sentries on watch in the jungle spots Kilo 23 on approach.''

Marine Sentry: "IFF confirmed. Contact is Pelican Dropship Kilo 23. Over."

Crow's Nest Controller{COM}: "Roger that. What's the word, Kilo 23?"

Hocus {COM}: "Sierra 117 onboard. Request priority clearance. Over."

The two marine Sentries bump their fists and smile.

Crow's Nest Controller '{COM}'': "Deck's yours. Come on down."

Kilo 23 proceeds to land in a hole in the ground.

Part 1:Walk It Off
It should be noted that there are actual Cavemen in this level go find them.

From the levels beginning, there really is only one way to go. It's a very linear space, and you shouldn't have any trouble following it. When the Phantom flies overhead, you should see a high rock on the right, just the right height to be jumped up to. Unfortunately, on Legendary you have a pretty useless weapon set, so just use the Pistol to open fire on the gold-armored Captain-Major Brute. As soon as the clip is empty, get in motion. About five or six Grunts will show up from the left end of the log in pretty rapid succession. Head shot them and then finish off the Brute, if you need to. (Often, the Marines will have finished him by this point, or at least softened him up a little). Once that group is dead, dual-wield a plasma pistol with your magnum and move forward until you hear the sound of a Phantom inbound. Quickly, back up and take cover behind the log, or the Phantom will make you bleed for it. As soon as it departs, move forward again. The Phantom dropped what will be referred to henceforth as a lance, or a Brute leading about four or five Grunts. Kill the Brute first. At this range, he should be easy to "noob-combo," being that he's unaware of your presence. The Grunts will probably panic, but some may not, so drop the PP and keep the magnum ready. Once everything there is dead, drop the pistol in favor of a Brute Shot. There probably won't be much ammo in it, but that doesn't matter yet. For the time being, just head left, through the foliage, and down onto a rock to claim the Blind Skull. Even if you've already gotten it, it can be an invaluable weapon here due to the massive melee damage. Once you've got it, get back up onto solid ground and head across the river towards the two Lances nearby. One is further forward, with Grunts on the sides and a Brute-Shot Brute on a rock. You can run in and make him hurt with the skull (my favorite) or attempt to noob-combo him. (The NC is always a safe, if cheap, bet, and you should use it when nothing else seems to work). The second lance is further away, with three Grunts and a Brute-Shot Brute who likes to hide behind trees. Watch out for him. Once they're all dead, drop the skull. Fill up on Brute Shot ammo and then progress on through the caves. Shortly, you will arrive at the second main encounter of the level.

This encounter and duel takes the form of a large, nonlinear valley, containing about fifteen Grunts (about half are asleep), five regular Jackals, three carbine Jackals, and five or six Brutes. This isn't an easy battle, but it shouldn't be impossible to manage. Some things to prepare: swap out the MA5C for a Carbine. Then, quickly move downhill and from tree to tree, killing sleeping Grunts. This will massively reduce the amount of incoming fire in the battle to come. Then, start by waiting for a small group of enemies to approach the clutch of plasma batteries on the far left side of the area, and carbine them for a multi-kill. So it begins.

The three snipers, being the longest-range foes, are your highest priority. One is quite close, on a rock one level down from the place where you entered the area—right below the Arbiter. In fact, the Arbiter may already have killed him. The two others are harder to find, hidden in the foliage on the ridge up at the top right side of the area. Pinpoint them by their shots, then zoom in and carbine-spam. (You have an infinite amount of carbine ammo in this area, so no need to hesitate). Once all three are dead, it's time to head down onto the valley floor. Fight your way across the river, taking care to look both ways for enemies as you cross. If you have picked up a Bubble Shield by now, I'd suggest that you deploy it on one of the raised areas just across the river to establish a beachhead. Target the Brutes first, then the Needler Grunts, then the Jackals, and then the regular Grunts. With the Brutes, you may want to use the Brute Shot melee to knock off their armor before you go for the head shot. By the time you've cleared the far bank of the river, you should have reduced the enemy forces to a single Lance. Swap out the Brute Shot for a Needler and use it to kill the Brute. Mop up the stragglers with Carbine fire. Once you've filled up on ammo again, move on down the path.

Up on the log above, Sergeant Reynolds is being menaced by a Brute. Needle the Brute, and then move forward under and past the log to get up the slope. There's a Carbine Jackal and a Grunt or two here, so be sure to kill them before moving on. Past this area is a section off to the left, out of which a few Grunts will come when you get near. Kill them and go into the place they came from. You can choose here to pick up the new, slightly better BR, or keep your carbine. I prefer the carbine, so I'll mention it in this walk through, but you can use the BR in its place if you please. At the far end of this area is a pair of Jackals (without Carbines, thankfully) and a rather sneaky Lance who I always get ambushed by. Again, use the Needler on the Brute and the Carbine on the Grunts. Follow the tunnel past the Cortana moment and you've completed this section.

Part 2: Charlie Foxtrot
To the left, right after you exit the tunnel, is a dead Marine with a BR and some grenades. Take them as needed and then head down the path until you find yourself overlooking a large area by the river. On the right is a dead guy who had a whole mess of frag grenades: five, I think. Lob them one after another into the Covenant below. Once you've done so, jump down from the ledge and take a left to find another frag grenade cache to chuck at your foes. Although there are two Lances in the valley when you arrive, it's hard to say exactly how many will leave when the Phantom arrives. Usually, at least the Brutes walk away. But they're not your chief worry. Across the stream are two Jackal snipers, and these guys have actual beam rifles that are capable of a one hit. Use extreme caution and terminate at range. Once they're dead and the Phantom has left, you're free to begin the second and most difficult phase of this battle: attacking the dam.

This part can be obscenely difficult on Legendary, not simply because of numbers (though you will be vastly outnumbered) nor because of firepower (although you will be like wise out gunned) but because you tend to get nasty checkpoints. There are two ways to get up onto the dam: just jumping straight up from below (nearly suicidal but not impossible) or walking up the left path (slow but safer). If you want to jump right up, then go ahead and do it. I'd recommend moving a lot, throwing grenades a lot, dropping Bubble Shields a lot, and watching your back obsessively. If you choose the left path, then beware of the four Jackals (two normal and two wielding carbines) on the path itself, as well as the lurking carbine Jackal up on a ledge to the left.

---

You should have picked up a Bubble shield somewhere along the line. Deploy it in this next area if under heavy fire. Once you're out of "sniper alley", you will come across Johnson's crashed Pelican, and a massive horde of Covenant Loyalist resistance. Pick up the Battle Rifle and Sniper Rifle at the crashed Pelican site before moving forward to the last section of Sierra-117. You do not need the Sniper Rifle here, but it is strongly suggested to grab it, as it will make taking out the Jackal Snipers and Brutes a lot easier.

Part 3: Quid Pro Quo
For this part of the mission you should have a sniper rifle and a battle rifle.

This happens fast so be ready as soon as the cut scene ends:

Look to the dam straight ahead of you. Zoom in with your sniper rifle and look at the right side near the building on the right end of the dam. There should be a Brute Captain Major standing there. Take him out with either one well placed sniper round or two. Next, remembering all of this happens quickly look at the left end of the dam (as far left as you can see, where the building on the left end of the dam starts). There should be a Brute Captain Ultra standing there. Take him out the same way as you did the major. Next, another Brute Captain Ultra will run past the one you just killed. Occasionally he will run past as you are killing the first, giving you the opportunity to get two for one (which is nice when you have no more than 24 rounds to work with). RELOAD NOW, even if you still have 3 round in the cartridge...... Finally, once the two Brute Captain Ultras are dead a Brute Chieftan (weapon class) will run out from the same area the second brute captain ultra ran out from.

He only has invincibility activated ~10% of the time and it is possible to take him out as he runs across the dam. He is sprinting so you have to make your first shot a good one to stop him in his tracks or slow him significantly. Three to four sniper rounds are enough to take him down if you land all of them on his head/shoulders. It is critical to land a first good shot on his head or he will most likely escape you. If you do happen to miss him don't despair... Look at the building on the right end of the damn where he disappeared into. About 30% of the time he goes downstairs and emerges from the door at the base of the building on the right side of the dam. Here is your opportunity to finish him off, all without having to step out of cover. After you take him out jump and take a quick scan of the area below you. Almost 100% of the time there will be another Brute Captain Ultra standing in the open. After you jump line your sight up on the ground in front of you so when you jump you barely have to aim at the brute below. One shot usually just knocks his helmet off, but jump again immediately and finish him off with a second shot to the head.

Now switch to your BR and plug the Sniper Jackal down in front of you. Switch back to your sniper, stay down, and wait until you can draw a bead on the rest of the snipers (there are about 5 of them).

You might not be able to kill the Chieftain with sniper fire, so be prepared for a long and drawn out close combat fight with him. However, it is possible to kill him by long distance sniping or BR fire (just wait until his invincibility runs out) It is also possible to stick the Chieftain, but only if you're very lucky. Plasma grenades do not adhere to a Chieftain, so the only way to stick him is to land it on the Hammer he wields. Lay down a pattern of Sniper fire until most of the Grunts, Jackals, and Brutes are gone, then jump on down, switch to your Battle Rifle, and move in. Your SR may be low on ammo, so exchange it for a Needler or Brute Shot.

About the Chieftain: if you see him charging at you and he's glowing white, that means he has his personal invincibility shield on and is preparing to make you a stat in the record book, so be prepared to run. Don't waste ammo or grenades on him when he has this shield activated, you won't do any damage. The best solution is to run around, or get to a high spot to avoid his Hammer and blast radius. A good solution (when the shield is down) is to lob some grenades at him while he's charging and follow up with some automatic fire. The Brute shot is another weapon that is very effective, but never try to melee a Brute Chieftain! The Needler can also be particularly effective, but sometimes the needles bounce off his armor. Anyway, if you forgot to get the SR, use the BR to take out the Jackal Snipers, one by one. As for the other brutes, if you have enough ammo left in your BR, you can use it to shoot them in the head, or else work together with Arbiter to kill them all, after killing the Chieftain. Beat down any Grunts that get in your way.

Upon rescuing Johnson from the makeshift prison the Brutes made, you will have one final engagement. Two Phantoms will arrive dropping a number of Brutes and Grunts. Engage them on the bridge and kill all of them to initiate Pelican Kilo 023 to fire upon the Phantoms destroying them easily. Hop aboard the Pelican to complete the level and begin the cinematic. Congratulations, you just beat Sierra 117 on LEGENDARY!

Glitches

 * The Stairway to heaven: there is another stairway to heaven glitch near the end of the level up where you can find the iron skull. You need three people; you go to the corner near the skull and get on each others heads. Start jumping and one of you will get up there, once up there you will notice a cliff behind you stand facing towards it then get the other two to kill them selves they should spawn on your head and with a bit of luck get on the cliff you can then go on to of the buildings or continue up the cliff to find a gigantic grassland you can now roam about. Also, in the grassland there is a big pit and you can also walk up invisible hills. If you choose to go on the building you can then walk along the edge of the cliff by doing this you are able to see a broken pelican on the river.
 * Specifically, to get the iron skull, near the bridge where the pelican picks you up, jump up onto the house with the glass windowed side where a sniper was perched, walk the top to the end, make a left then a right as the building merges into the sniper tower and pick up the iron skull.

Trivia

 * For the first time in the entire Halo series the player doesn't begin the game in space but on the ground.
 * The multiplayer map Ghost Town is based on, inspired by, and is also in the same area as Sierra 117.
 * Note that the level is called Sierra 117; Sierra is the word used in the NATO phonetic alphabet to represent the letter S, which, when used in a military sense, generally stands for "sniper." However, in Halo 3, it is S 117 which corresponds to SPARTAN-117. This has been confirmed in the second Bungie Podcast.
 * In the August 2007 EGM Halo 3 Story, Sierra 117 was mistakenly said to be the fifth level in the Halo 3 Campaign.
 * Jumping into the deep water at the point where the Pelicans are shot won't kill you or even lower your shields. Also you can see fish swimming and even kill them. (These are what makes the small yellow dots are on your motion tracker)
 * If you go into the water where the pelicans were shot down, and if you walk into the waterfall, look behind you, and if you position yourself just right, the water will disappear. (This has been known as the flying fish glitch)
 * Quid pro quo is Latin for "something for something".
 * After Johnson is shot down, when you get to Jackals with carbines if you climb up to where the Jackal on the left rock face in a small corner is a family of cavemen with one carrying a teddy bear.
 * The Achievement "Landfall" is the same name as the Halo Shorts Series, Halo: Landfall.
 * The level is home to two skulls. The Blind skull can be found on a ledge hanging over the precipice following the second encounter of the level. The Iron skull is found on the ledge above the area where Johnson is imprisoned toward the end of the level. When the Iron skull is picked up, the Achievement "Iron" is earned along with 10 gamerscore.
 * The level contains several easter eggs. These include a small group of Cavemen and trees with initials carved into them. There is also a lone caveman.
 * Two examples of the trees that have carvings in them are a carved heart that has the intials MF inside the heart and another carved heart that has M + L 7-16-95 inside.
 * The river in the area is the Nkuu river or one of its tributaries, where the Blind skull can be found, is located inside of the Republic of Tanzania's borders.
 * The compass on the assault rifle is inaccurate - it is out by roughly 90 degrees. Using the compass alone, one would estimate their position as being ontop of Shira peak which is of course to the West of Kibo peak. If you scan the horizon, then you would see Shira peak to the left of Kibo peak.
 * Master Chief didn't come down from the sky in his armor alone. Right at the beginning of the game, a huge chunk of Forerunner ship, the Dreadnought, metal or alloy of what appears to be a balcony, intact with bracing on the underside, is the makeshift heat-shield used by Master Chief.
 * Johnson grabs a Needler when you rescue him; this could be a reference to the level Truth and Reconciliation, where Captain Keyes grabs a Needler when you free him.
 * When you reach the cutscene of Quid Pro Quo, you can actually skip the cutscene while the Chieftain is still attacking Johnson. You can snipe the Chieftain then, and he can't do anything about it because of his scripted motions. This is the easiest way to kill him on higher difficulties, namely Heroic and Legendary.
 * If you were to stick a grenade to the brute holding Reynolds at the right time, it will kill the brute, but Reynolds will swing around as if still being held by the brute. When the animation ceases, he will stand still and do nothing, but if you move him, he will start walking around. This can only be done on Legendary because that's the only way to obtain plasma grenades during that point in the level.
 * At the area where the Pelicans are attacked, an additional Jackal sniper (armed with a Beam Rifle) will spawn if the player takes too long to get through the area. This only occurs on Heroic or Legendary difficulty.
 * Even though the time line takes place in the morning, the actual in-game background scenery tells a different story. If you use the position of the sun, the orientation of Mount Kilimanjaro and the Chief's position at Blind Skull, the time would be late in the afternoon, near the winter solstice. So obviously the sun is in the wrong place.
 * At the start of the level, players can hear animalistic howls. Instead of native Earth animals, as thought, it is actually nearby Brutes.
 * Even if you are playing on Legendary with the Thunderstorm skull active, the first Brute will always be clad in the gold armor of a Captain Major.
 * When you get to the dam where you have to rescue Johnson, if you skip the cutscene where Johnson tries to fight the Chieftain, if you look at the supply crates in the room (works best with a Sniper Rifle), you will see Johnson get "teleported" to the wall behind the plasma shield.
 * There is a lone caveman on this level. When Echo 51 has landed, take your Sniper and zoom at the bushes on the cliff to the left of Echo 51 and you should see him. You can search for "Halo 3 Lone Monkey Man" on YouTube to see how to get to him.
 * Sometimes Echo 51 will kill you with it's rockets by accident if you're near a enemy when the Pelican arrives.


 * At the dam(where you go for evac,not the one where you save Johnson) ,if you jump in the water you can still live. It provides a good flanking spot and if you are lucky a machine gun turret may be in the water from the pelicans when they were hit.
 * Near the beginning of the level, you can find a small family of cavemen, one of which will be holding a teddy bear( no effect on gameplay)

Achievements
Landfall - "Landfall" is an achievement awarded to the player for completing the level on the Normal, Heroic, or Legendary difficulty. It is worth 20 Gamer points.

Iron - "Iron" is an achievement awarded to the player for finding the Iron Skull. It is worth 10 Gamerpoints.

Guerilla - "Guerilla" is an achievement awarded to the player for earning 15,000 points or more in meta-game free-for-all scoring. It is worth 10 Gamer points.

External
-A leaked video from E3 2007.