From Halopedia, the Halo wiki
For this mission you play as The Rookie. Your objective is to locate your squad. In order to do this you must locate certain clues that will trigger flashback missions. Your starting weapons are the M7S SMG and M6C/SOCOM Pistol. Mombasa Streets is an open environment level, where you can choose which missions you want to do and what order you wish to do them in. In order to achieve the Legendary Shield you only need to complete the first section which will be detailed. If you choose to complete the rest of the open environment, this walkthrough will provide you with tips on survival and how to make it through some of the more perilous areas on the map.
That's the last time I take Dramamine before a drop!
You start the mission in your pod. Hit the four buttons to release your canopy, then jump down. You're hurt and need to heal up. Turn to your right and immediately heal up at the OPTICAN station. Turn on your VISR, most of the city will be dark to you and you won't have a map yet but enemies in your visual range will be highlighted in red. Move to the right and pull out your pistol. Look down the street and a patrol consisting of a Brute and several Grunts will come into view. Hide in the little corner in front of the bend at the stairs. When they are behind the truck, quickly run up and assassinate all of them If the Brute is near the back, assassinate him first, because if the other Grunts spot you then they'll be more likely to panic. As you approach the roundabout, circle left (counterclockwise) and take out the squad there. Come back to the right side where you will see a set of stairs on a corner. There will be two squads approaching at the same time. You cannot avoid this fight. If you're a skilled Legendary player, engage with Grenades and your Pistol and you should prevail relatively quickly. Do not go to the left of the corner, it is a dead end street and you will be trapped with little cover. If you're not confident in the direct approach, turn right and sneak around to the back of the formations. You should be able to divide the groups and with a little surprise on your side kill them relatively quickly.
Once you've cleared these groups, a message will appear on your HUD, telling you to make contact with the Superintendent. You will hear a phone ringing nearby and it will be highlighted yellow. Go to it and answer. You will download the city map and objective data, and while your VISR capability is turned on, the city will be outlined in a muted yellow to help you see. Once you've completed this, head back to the right side of the corner with the stairs, you will see a side street that is well lit on the left, go down it and on the right you will find a door that opens. Head through the building, and out into an open court where you will encounter Grunts. Kill them and go into the building on the other side. By now your VISR should have a faint blue glow and be pinging as you are near your first clue. Head up the stairs inside and watch to the right a door will open revealing two Sniper Jackals. Kill them and if you're doing the campaign take the Beam Rifle. Keep going up and when you see it grab Dare's Helmet. Congratulations, you've just earned the Legendary Shield for Mombasa Streets and you're one step closer to completing the Campaign on Legendary.
Hey Bub, We're not done yet!
So, You have your Legendary Shield, and you've completed the campaign already, why not just bypass completing the rest of the level and skip from mission to mission? Well where's the fun in that? Once you've completed Tayari Plaza head back down the stairs and out into the Crater Plaza. You'll notice that you're currently where Buck's mission ended. Look around and you'll notice that the Superintendent is directing you with the billboards. Head through the blast door, and take care, your about to encounter your first multi-Brute squad escorting an Engineer. Be careful as the Brutes will have an Overshield. Kill them quickly from range with your Beam Rifle, and move towards the waypoint on your HUD. Now you are truly in the open environment. You can use your map to go from mission to mission and find the fastest, or quietest way to each clue. You will be faced with the choice of running or fighting, and you'll be surprised at how many times fighting is easier than running. Keep at least one ranged weapon, two is better, but one will allow you to investigate new map areas without exposing yourself to danger. Jump Brutes and Brute Stalkers are the only Brutes with coverage of entire areas, so if you can kill at range, regular Brutes will never get a shot at you. (note: Causing a Brute to go Beserker will make him charge out of his area but quick, accurate, shooting will take them down before they can get to you). Each of the waypoints you are guided to will be trigger a mission when you find certain items:
Where's the Beef? (Or, Running on Empty)
So you've followed all the waypoints and all you have is an empty Spiker and a Plasma Pistol? Have you been avoiding the sirens and ringing phones because you're afraid they're going to draw attention to you? Well now you need to go back to these spots to collect audio logs. Collecting these does more than unlock the backstory to Halo 3: ODST and get you achievements, it also unlocks Supply Caches around the map. Inside these supply caches you'll find grenades, ammo for your SMG and Pistol, Sniper Rifles, Rocket Launchers and even a few Mongooses. Supply Caches are equipped to resupply four players completely if they are all out of ammo. The more audio logs you open the more caches you'll have access to, and the better chance you'll have at surviving.
Is All That Firepower for Little Old Me?
So you've made it through NMPD HQ. Ask yourself a few questions. Do I have full health? Do I have a full SMG and Pistol? Do I have a Mongoose? Have I mapped out my route to Kikowani Station? If the answer to any of these questions is no, stop. Go back and find a cache, load up, and pull up your map to determine your route. Once your full up, hop on your Mongoose and burn rubber to Kikowani Station. Don't stop for anything. You're fast enough that you can outrun any enemies you may encounter. Once your there, hop off and go directly to the item to start the mission.
Once you've completed the mission, you'll be back outside the station. Your Mongoose will be a little ways to the left. Hop on and head back to the right. Avoid the Grunts then turn down the street. Don't go too fast just yet. There will be a Hunter in the square ahead of you, but turn left down the first street and start to gun it. Your going to speed past two Jump Brutes, then right to the top of the street and on the right will be the entrance to The Data Hive. The reason you're going so fast, is as you crest that hill, if you glance to your left you will see Fuel Rod Grunts, Sniper Jackals and enough Brutes to remind you of a King Kong casting call. Winning this fight can be costly, and is basically a waste of time so skip it and hop into the shaft.
Now you've really finished Mombasa Streets on Legendary.
Notes for play on Legendary
Notes for Lower Difficulties