MISSION 01 - Osiris
Advised weapon combo: Battle rifle + boltshot (initially) ---> supressor + light rifle (when light rifle becomes available)
Skulls - 1
Intel - 7
After the bombastic introduction cinematic (that we all wish we could have played), we take control of Spartan Locke as he and his team attempt to rescue Dr Halsey, creator of the Spartan program from Jul, a covenant leader. When gain control after disemboweling an elite with an energy sword take a moment to orient yourself and get used to the movement and aiming controls. You start off with a battle rifle and a magnum, a good range combination but unlikely to find ammo refills on the battlefield.
Hug the right wall from your starting location to find a grunt holding some intel on the ground against the right cliff face with a covenant ammo cache (storm rifles) next to it. Walk up the slight slope until you reach the cliff edge and see the covenant and promethean forces going head to head. Continue along the cliff face until you emerge from between two rock piles to see a promethean crawler in combat with a covenant jackal on the rocks ahead.
X (when downed) - Call for revival
D-pad up (when targeting enemy) - Focus fire on that enemy
D-pad up (when not targeting enemy) - Move to the marked location
Objective: Retrieve Dr. Halsey
Quickly pick off the distracted combatants, but hug the left rock pile from where you entered while you do so to avoid fire from the ship overhead. After a few seconds, the ship will take off allowing you to take on the enemies without being carpet bombed. A jackal will be firing from a mound to the left (with a stock of shock rifles next to him), while an elite runs around in the central area in front of you. A couple of crawlers will also emerge from behind the mound to attack for you to deal with as you move up.
When you progress past the mound four crawlers will start firing at you from multiple directions. Take cover near the ledge to the right, or behind one of the rocks jutting up from the snow if you can't reach it safely. Kill off the nearby crawlers, then pick off the one on the ledge a little ahead.
After receiving the 'all clear' start moving up the metal ledges of the snowy slope. Against the right wall of the path are a pair of suppressor weapon stands which you might want to replace your magnum with (as there are plentiful promethean weapon ammo caches ahead in the level). After jumping up the next ledge past these, two soldiers will phase into view in front of you and then immediately flee. Don't bother wasting ammo on them.
Continue up the snowy ledges until you reach a point where you have to perform a ledge grab. This simply means jump towards a ledge and press A again when close to it to grab it and pull yourself up. The two fleeing soldiers will poke their heads out, and then abruptly vanish as you enter the alien structure at the top.
Two boltshot racks will be on the wall directly in front of you (also a valid replacement for the magnum), these can be useful for players just starting out as the bullets home towards targets quite effectively thanks to it's low kickback when fired, whereas the kickback from firing a suppressor makes it harder to consistently keep your homing shots on target (strange as that sentence sounds).
Moving past the boltshot racks, your path ahead will be blocked by a wall of icicles. This is where the game introduces the spartan charge. Simply sprint at the wall from a decent distance and press melee (RB) when you are close to it to slam into it, breaking apart the wall of ice.
On the other side of the wall, a soldier will be waiting to greet you. Immediately start firing at him, while moving for the cover of the rock wall to the left. If you picked up the boltshot earlier, it will be very effective at this range. After finishing him off move further ahead to the cliff edge, looking on the ground next to the cave wall on the left to see the body of a fallen elite with some intel with a carbine next to him you may want to use. Look into the distance to see the battle is still raging between the two forces.
Turn right and walk along the cliff-side path for a few seconds to be greeted by another soldier firing a suppressor at you. Back up and use the rock wall to block his shots, or run forward and use the rock formation on the left as cover. A boltshot or battle rifle will work well against the soldier from this medium distance, so start unloading on him with one of those if you have one.
Don't forget your team commands either. Even on legendary difficulty they can help take out lone enemies by firing from multiple angles, drawing the focus away from you and allowing you to take clean head-shots. Just don't run them right into the middle of an enemy swarm or a group of hunters and expect them to win. Always try to keep at least one of them alive at all times as well, as if they are all dead you cannot be revived. Although the AI is surprisingly suicidal with it's positioning when reviving you, so don't count on it.
As you move up, another couple of crawlers and a soldier will join the fray. Try and take the ledge leading up to the right if you can as it has decent cover and provides a good line of sight for the area. Plus there are another couple of suppressor and light rifle gun racks here for you to replenish your promethean ammo. Grab one of the light rifles to replace your battle rifle here, as you are probably nearly about out of ammo for it.
The light rifle acts in a similar fashion to the covenant's carbine, making it most effective between medium and long range. This makes it perfect for pushing forward in this area, as you will often not want to get close to soldiers or crawlers in higher difficulties. Start firing off head-shots at the soldiers in the area from your position.
As you move along the ledge, you'll see more soldiers appear on ground level, with another soldier up on a ledge jutting out from the cavern wall. Target the one on the ledge first, as he has a light rifle of his own. After one of the soldiers falls, a group of four or so crawlers will emerge in the lower area, along with another soldier wielding a light rifle on a mound in the center of the area.
At this point, I should remind you to be wary of the promethean habit of teleporting/ leaping around. This can be dangerous at times if a crawler or soldier teleports behind you and opens fire. So make sure to use your eyes and radar to prevent these kinds of back attacks. Target the soldier first (unless the crawlers reach your position), and try to dispatch him quickly with your light rifle, leaving you free to mop up the crawlers in the lower area with your boltshot or suppressor.
A couple more soldiers will arrive to support the crawlers in the area underneath the central mound, making things a bit more dangerous. At this point you may want to temporarily move down into the lower area to clear out any remaining crawlers (so they can't flank you while you try to deal with the light rifle soldiers). The piles of rock should give you plenty of cover from soldier fire as you weave between them, finishing off crawlers.
When the crawlers are gone, you can return to the ledge and carefully take on one of the soldiers at a time by peeking out from the side of your cover (so they don't all hit you with light rifle shots at once, killing you). Methodically take out all the soldiers you can see from this position.
Why are we doing this slowly, staying far back from the enemy instead of racing in? Well, for those on higher difficulties, two or three light gun shots will kill you instantly. Also, if you die close to enemies, your AI companions have a baffling habit of getting killed while trying to revive you. It would be rather funny if it didn't lose you progress each time. Of course, if you are on a lower difficulty, feel free to use your own method of attack.
Once the light rifle enemies are disposed of, you can carefully move forward along the lower area, dealing with the remaining crawlers and suppressor wielding soldiers. When you reach the central mound where the light rifle soldiers were firing from, you should get a checkpoint.
While you can progress by going left, right or over the mound. I would advise you avoid the right path, as it is very narrow and has no cover with a light gun soldier lining up along it, making it a deathtrap. Instead you can jump up onto the mound to pick up some fallen ammo for your light rifle, before retreating and taking the left path. This approach allows you to deal with one enemy at a time with your light rifle as you move around the mound.
Just be careful of the light gun wielding soldier on the raised area ahead as his shots still hurt. You also need to watch out for enemies leaping up/ teleporting onto the mound and then firing down at you from above. Once you've taken out the light rifle wielding soldier from your position on the left side of the mound, you can leap on top of it and start raining down death on the remaining enemies with your light rifle (there are several rocks you can use as cover if incoming fire gets too much). There are also a couple of suppressor/ light rifle racks at the front of the mound to replenish your ammo supplies if they are running low.
There is also a icicle wall in the narrow path to the right of the mound that you can smash into with a spartan charge if you wish, that leads to a weapon cache holding a scattershot (promeathean shotgun), you will be pretty exposed in there though so be careful with your timing. After clearing out most of the crawlers and soldiers in the area, you'll still have two in front of the entrance to a forerunner security station at the back of the area to deal with. You may need to use grenades to get them out from cover before peppering them with light rifle shots.
For another bit of intel, you'll need to jump from a large rock to the right of the forerunner security station, up to a ledge where you'll find the body of a grunt and a data pad (intel) on the ground beside it along with a carbine if you need to restock. If you take the ledge to the left of the forerunner security station, you can find a skull overlooking the aerial battle in front of the cliffs. Once the area is clear, you can move forward into the ruins.
Walk down the ramp and approach the door to find it securely closed. Luckily Locke is the new master of unlocking. Objective tracking will be demonstrated here, simply press down on the D-pad to point out your objective (and nearby ammo locations). You'll see the marker pointing to an access point on a platform above the locked door. Stride back up the ramp and then use the platforms to jump up to the access point, interacting with it to open up the door below.
Immediately as you walk through the door, you'll see promethean weapon caches to your left and right. Restock on ammo and grenades before moving forwards into the cavern. Turn to the left after seeing the massive ship moving away in front of you. When you see a puddle of water on the floor with a lower ledge to the right of the main path, drop down to find some intel at the end of this lower ledge. Jump back up to the main path, and keep moving further into the snowy cave.
After a ledge grab jump you will see two exits from the cave in front of you, looking out to the massive ship you saw just before as the covenant and promethean forces fight on the field in front of you. Use their current distraction to start picking them off with your light rifle from the right cave entrance (as the left leads to a lower level area where you can be back attacked/ fired down on). While the large ship is firing, stay in cover. Move over to the edge of the upper area so you can overlook the lower path where the other cave mouth exits to see an elite and jackal for you to destroy. Be very careful of the trio of light rifle soldiers on the raised areas of the path further along the area, as their combined shots can be deadly.
Use this position to start taking out these light rifle enemies one by one (peeking out from cover so you engage one at a time). Watch out for a promethean soldier at the back carrying a splinter turret (think of it as a grenade launcher or less damaging fuel rod cannon), which will fire arcing balls of light that deal nasty AoE damage if they explode near you, or just kill you if they hit you directly on higher difficulties.
While he shouldn't be too much of a problem thanks to your distance away from him (due to you having plenty of time to move away from his incoming shots), you will still want to remove him before you start moving forward. Be cautious before descending to the lower path (as prometheans will often teleport past where you are), make sure to check your radar before moving up.
In this lower area you'll see several icicle walls you can smash through for cover/ shortcuts if you wish. The main reason for taking this path to move up is protection from the ship's (Kraken's) attacks if you take the upper route. Move along the base of the trench, clearing out the remaining crawlers and soldiers. When the trench starts to open up at the far end, you should get a checkpoint.
More crawlers will descend into the trench at the far end, but a suppressor or boltshot should chew through them in rapid succession. When this small wave is defeated, the Kraken will fly off, leaving you in peace. Pick up the dropped splinter turret if you can to finish off any remaining enemies in the immediate area. Carefully move past the edge of the trench and you will see a soldier on a splinter turret halfway up the cliff face to the left, with another soldier next to him. Pick off the turret using soldier first with your light rifle, before focusing on the other soldier.
As you move up closer to where those enemies were, you'll see another ruins entrance to the left of their position. Three soldiers will be standing in front of the entrance, another soldier will try to flank you from a small raised area to the right and crawlers will just be wandering around making life more interesting for everyone. Terminate the flanker first, as he can be a problem otherwise, before turning your attention to any close by crawlers. After that, you can pick off the trio at the entrance at your leisure. Just watch out for a pair of additional soldiers spawning on the ledges to the left, one on the lower area and another on the splinter turret above.
When all the enemies are cleared away from the doors to the forerunner structure, head right from the doorway and climb up the ledge. From here, look down the little slope towards the cliff to find some intel. Enter the ruin entrance when you are done and follow the corridor inside.
You'll enter a small room at the end of the corridor. Immediately turn right towards the window to find some intel on the floor. Backtrack to the other door in the room, noting the dual ammo caches on each side of it. Make sure your light rifle is fully stocked, as you are definitely going to want it here.
As the door opens, you'll see a knight directly in front of you on the other side. As the squad will continually tell you during this fight, you need to aim for the glowing points on a knight to damage/ destroy it. Meaning you have to shoot both shoulders, then hit them in the mouth when they roar or repeatedly in the back. Firing at them anywhere else does little/ no damage (unless you are using a weapon with an AoE effect, such as a rocket launcher). A good strategy is when you hit the second shoulder, they will often roar. Giving you an opportunity (if you are skilled enough) to fire a shot down their throat, killing them instantly. Otherwise you have to do the slow back attack method.
The good news is that the ammo caches by the door should be sufficient to get you through most of the upcoming fight (there is an additional cache along the walkway to the left inside, but that is better left until some of the enemies have been thinned out). Use your good cover position at the doorway to start by taking out the soldier on the turret in the middle of the room, then turn your attention to the three knights that are moving around the area. They generally won't do much unless you get close.
This gives you the opportunity to blast them repeatedly with the light rifle without them doing anything in return. The only possible danger is the wandering crawlers in the room which occasionally leap up onto the upper walkway where you are and attack. Make sure you at least destroy all the knight's shoulder armour before moving into the room. Although if you are accurate, you should be able to kill all three without even setting foot inside.
When only one knight remains, a teleportation field (purple mist) will announce the arrival of additional enemy forces. More crawlers and another pair of knights will arrive to keep you company. Repeat the same tactics against them that you did before. Moving into the room to start clearing out the crawlers. If there are any knights still standing (those that you missed the mouth shot on) wait until all the crawlers are gone before trying to deal with them.
When only the knights remain, you can do a few things to make them expose their backs. You can order your squad to the other side of the room, splitting the enemy focus. You can order the squad to attack the knight directly (bad idea on high difficulties) and try to flank it. Or you can try to circle around the outer edges of the room, using your nearby squad members as bait as you try to shoot it's back. There are also grenades and other approaches, so pick which method suits you best and go to town on those knights.
Another pair of knights and crawlers will spawn in when only one knight remains once again. Rinse and repeat the previous tactics and clear the room. Aren't you glad those ammo caches are there? You can also find some intel on a ledge to the right of the door leading out of this room, next to the body of an elite. When everything is finally over, walk to the back of the large room and up the ramp at the end to trigger a scene and complete the first mission of the game. Piece of cake, right?