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Level Start and Commons R-01
After skipping the cutscene, enter the next room and wait near the yellow door without being too close to it. After it explodes, enter the next room and obtain a Plasma Pistol as quickly as possible. If you're new to the game, it'll be easier to dual wield two Plasma Rifles.
Jump up to the balcony above the yellow door and wait for two Elites and two Grunts to run into the room before dropping down behind them. Try not to get spotted by them in the process. If you don't get a plasma pistol in here, drop down in the next room, head left, and kill a Grunt for it. Otherwise jump up to the balcony on the right, go near the end of the path, jump down and run straight ahead. Noob combo the lone Elite. You can melee/backsmack him to conserve your plasma pistol's battery.
Noob combo the Elite, BR the Elite and Grunts coming out of the tube, quick reload, and BR the second wave. BR the two Grunts that were already in the room if the marines didn't kill them. If you're using the dual wield strat, just shoot all the enemies. Look at the Malta to make it explode sooner, don't stop looking until it's blown up. Pick up four Plasma Grenades on the balcony. You can also retrieve them by being underneath their location and jumping. The three frags near the entrance can be retrieved from below too. Head towards the locked door at the end of the room without being too close to it.
Stay up top and focus on noob comboing at least one Elite per wave. Kill the Grunts when you can. You can kill a Grunt while the charged projectile is tracking it's target. Toss a frag to intercept each wave while continuing the above pattern. On the third wave, the game starts a timer that will eventually spawn one white Elite and two Grunts in the tube regardless of how quickly you clear the room. Noob combo the white Elite and BR two Grunts. Promptly replace your plasma pistol for one with more charge. While looking at Malta, make your way up to the balcony and retrieve plasma grenades. If the marine up here survived, you can kill him yourself, he has a chance to drop a frag or two. Head to the area above the door. When the door explodes, drop down behind the enemies and proceed. Make sure to pick up the BR ammo near the turret!
BR both turret Grunts, BR Grunts, but prioritize killing the Elite to make the next wave arrive sooner. Either throw a plasma grenade where the enemies land or stick the Elite while he's in the tube. Kill any remaining Grunts. Look at the Athens, it's the same case as Malta. Head into the back room to grab frags then go down either stairs.
This hangar is a disaster waiting to happen. Note that the turret Grunts drop 100 charge plasma pistols. They will eventually despawn if not picked up. You can toss a plasma grenade towards the enemies before retrieving the guns. Dual wielding plasma pistols, jump up to the balcony and drop one of them near the large green box on the right. Noob combo Elites, BR Grunts, toss a grenade for each wave. You can stick Elites that are taking cover against boxes in plain sight. Strafe to dodge enemy return fire. Watch out for Grunts sending plasma grenades your way, the explosion can be deadly and can knock off your plasma pistol if it lands near it. On the third wave, the game will eventually spawn two super lethal white Elites and a gold sword Elite (the white Elites will be flanking the Goldie). After killing most of the enemies, dual wield your plasma pistols, charge them up, and aim for where the two white Elites will be when they spawn. Finish off the Goldie, collect his sword, and it'll finally be over. Go to the back room to retrieve frags. Look at Athens, look at it, look at it. If you remain up top long enough, you can get a checkpoint before proceeding into the hallways. If you want to go faster, wait at either door at the bottom of the stairs and cancel off the Elite when it opens.
Hallways, Armory, and Commons B-01
Run to the armory, watch Gunns die, get his shotgun. Run through the next room, heading straight forward. When you reach the end, you can jump onto the small ledge to the right or grenade jump up using a plasma grenade.
Stick the first Stealth Elite then go to the other hallway and sword the second Stealth Elite. Stick/BR the two Elites up top. Note that one of these can spawn as a white Elite. Upon entering the next room, you'll get a checkpoint. Sword fly to and over the turret Grunt (YXR+A). Revert if you don't get it in time. If sword flying isn't an option, you can jump onto the ledge to the right and up to the balcony. Jump across to the turret area.
Sometimes you can get a checkpoint right before the two large green boxes in the next room.
You need to get down this hallway quickly, if enough enemies are killed before you reach the end, several enemies will spawn ahead of you. Sword fly into the Elite or sword fly to and jump over a Grunt. Sword lunge both Ranger Elites. There are several ways to reach the room with the Drones:
Method 1: Jump up the ramp ahead of you, grenade jump to the top of the space station and head to the door.
Method 2: If the Elite Ranger outside is floating above the structure that you entered space from and he's not moving, you can sword fly off of him. You can do it from the ramp or the nearby crate.
Method 3: If the Elite Ranger is underneath the structure, then you kill him with your sword and BR the second pair of Elite Rangers that arrive. This is also helpful if you're unable to utilize sword flying.
In this big room, several Drones will fly up when you cross the yellow line. You need to kill at least four or five Drones to trigger the door at the bottom to open. You want to get to the yellow door right as it's opening, there will be two Elites and several Grunts inside. Approach the edge, bounce a frag off the floor, and keep moving forward. Turn around and BR one or two Drones. You can tell if the door is open by the red light glow near the switch. If the door doesn't open, kill a few more Drones. When the airlock door opens, either toss a frag so it lands in the midst off the enemies or stick one of the Elites, then switch to your shotgun and clean them up. Make sure the last enemy dies before the airlock door fully closes. Staying in the middle of the small room, you'll have skipped some dialogue to open the door sooner.
Heading to the right, throw a frag towards the yellow line where the Drones emerge. Then throw a frag under the platform near the stairs, a Drone usually flies down here. Head down to the lift, kill a few more Drones from down here if the door hasn't opened. Sword fly to a Grunt in the airlock, jump behind either door frame, and kill anyone who's still inside.
If sword flying isn't an option for you: Kill all the Drones and let the lift come up. You can stop it by using the switch. Staying on the top level of the elevator, you can noob combo the Elites and kill the Grunts. The Grunts tend to throw grenades at you if you're up here. You can damage/kill some of these by bouncing a frag off the floor. Once the area is cleared, drop the sword for a plasma pistol with decent charge.
Space (second time)
The current strat is to juggle a plasma pistol to a certain spot and sword fly off the turret Elite while swapping the sword for the plasma pistol. This will take some practice. Delay the checkpoint you get in the airlock until the door has opened.
The safer strat is to noob combo. There are two plasma pistols with 100 battery available in the airlock. It helps to bring a plasma pistol with you to give you a spare to use for the bomb room. With careful aim, you can noob combo the turret Elite. Noob combo the other two Elite Rangers. BR the next pair of Rangers from a safe distance.
The bomb room is guarded by four Elites (the dual wielding one has a chance to be a white Elite) and two Grunts. Toss a frag at the initial enemies, BR them, then go on a shotgun spree. You can use grenade sticks on Elites that keep their distance. The level usually ends when everything in this room dies.
The bomb room is guarded by six Elites. Noob combo the first Elite then head left. Carefully noob combo most of them from this position, use the crate and walls for cover. If your plasma pistol's battery is about to expire, you can trade it to a marine in the back room and kill him to reset it.