Act 1: Briefing
Considering this is The Boss Extreme Embleme walkthrough, I'll assume you all know how the chapters go, having completed the game at least once (Maybe twice or 3 times) in preparation for the challenge that lies before you. You should have every weapon stocked up to as full ammo as possible as The Boss Extreme mode only allows a certain amount of ammo for the entire game, unless you find more. Every soldier is more vigilant, every sound more pronounced and every corner more ladened down with troops than any other difficulty. Let me just emphasise that everything in a BBE run is about speed and accuracy. It's about knowing where you're going and getting there with pin-point precision. Good luck.
 Ground Zero
Lets get straight to it. Jump off the truck and skip the first cutscene to dive right into the action. Crawl under the truck on the left and pick up the AK47 on the ground. After a brief cutscene (Which you will obviously skip), equip the AK. Aim it at a wall and waste the ammo you have in it. The reason for which you will find out shortly. continue on across the road and to the corner to trigger the cutscene where the ghekkos attack. Run straight across behind the first Ghekko that drops and through the first ruin, heading off under the rubble that you can crouch under. On the other side of that part if's as simple as heading off into the door and triggering the next cutscene.Now.. that's the easiest part over with, now let the fun begin...
 Red Zone NW Sector
At this point you're given the OctoCamo. Bring up your weapon menu and equip the magazine you got for wasting the ammo from your AK in the last paragraph. Run around the corner and throw the magazine at the remains of a car across the road. Run in the door as the two soldiers hear the magazine drop and turn around. The sound of the magazine will stop the un-skippable cutscene of the Striker pulling up, giving you valuable time to run out the door where the two guards you just distracted should be. Once they say ' Lets go investigate ', you can run out and straight down beside the Striker as it pulls up. Crouch walk in the door beside the van -This part may take a few attempts, but trust me on it- sneak up on and Stun the two guards with your stun knife. Then run straight on our the back and towards the RedZone.
 Red Zone
Immediately you're placed in a position that requires you to go prone. Well, what are you waiting for? Fill up your camo index and crawl to the right like there's no tomorow. Eventually, there'll be a gap in the concrete wall to your left, with a chain link fence filling in the space. Be careful, and wait for the guard in that area to make his rounds. when he can no longer see you, crawl (or crouch walk if you're daring) passed the gate and manuever your way past the guard up ahead. This should be relatively easy, if you wait for him to turn around and keep a full camo index, crawling your way to the right & staying behind the stone pillars. Easy enough? Well, when it's safe to proceed you need to get to that Mk. II... But wait! IT'S A TRAP! there'll be two pmcs that crouch behind the corner of the bombed building, just before the Mk. II. Then two more will show up. Just lay low, and let them pass. Done? Good. now, let's go meet with that recon terminal.
After you meet up with the Mark II, you can feel comfortable in equiping your facecamo... though only for a little while. Sneak past the pmcs, and continue to hug your right wall, letting your camo index fill up in intervols. When you get to the part with the militia fighting the pmcs, equip your M.E. disguise, and walk on by.
That M.E. really is useful, huh? Keep walking, 007.
[EDIT] It was recently brought to my attention that some people lack the M.E. Disguise. You can find it in the militia safe house, in a locker with other guns and items.
If that's too easy for you, or you still can't find it, here's the walkthrough for this level:
The level starts off with you walking through a tunnel. There's a guard there. You can either hold him up, or tranqualize (do NOT use emotion darts or knock him unconscious with the stun knife, as it will instigate a caution.)
Proceed down the hallway. Make sure subtitles are on. When you hear someone say something, hide (the places to hide are fairly obvious, and with facecammo it's easy to get 99%). The only tough part is sneaking around the guards talking about the wing flap, and the guard with a gun bought from Drebin. For these guards, crawl around, then tranq the guard that faces your direction, followed by the next guard. The rest should be easy.
 Urban Ruins
This stage is a cakewalk. Honestly. Keep that M.E. on, and run through the ruins. GENIOUS! After you trigger the cutscene, save. now, stay to the right, again, and keep that M.E. disguise on so the militia doesn't gun you down. after you pass the car, on the back of the corner of the building is a ladder. use that to climb up, jump over the box, and put on your octo camo. hop down, and crawl to the right, under that wrecked car. continue onward, and make a left down the first alleyway. There should be climbable boxes in it. At the end of this alleyway, go prone and creep to the right. once your index goes blue it's safe to crouch walk if you like. Keep moving, and eventually you'll come to an area where the pmcs are antagonizing the malitia. use the mosin-nagant to eliminate the window & bridge snipers, and the Mk. II on the two hiding behind sandbags... not nescesarilly in that order. Anyway, when you clear this area, crouch over to passed the bridge, and hide NEXT to the garbage can, triggering the two pmcs that emerge from their hiding hole. Let them pass. Crawl a little further, and be sure to have your solid-eye on so you can keep track of enemy movements. two enemies will just plop out of the same place the other two did. Two shots with the Mk. II eliminate this nusiance. Onward you go! Two-four more pmcs are headed your way down the alleyway as you round the bend, so creep over and either let them pass or give them a taste of that sweet sweet neutralizing syrum. Crawl your way to advent palace via ditch and bam, you're done.
 Advent Palace
I hope you have Mosin & Mk. II ammo, and the Solar Gun, cause' you're going to need them. Immediately after Meryl says "Move" move to the right, as fast as you can. Two FROGs drop down in your path. Equip that solar gun of yours and give them what for. Keep it charged as the next wave comes in, and subdue the rest of the enemies as they come. It's actually possible to get out of this part of Advent Palace with 100% health, so shoot for that. If you have the "Metal" Camo downloaded, equip it. It's very useful later on. Anyway, after you clear this area and head down the stairs, toss a smoke grenade over the other area near the stairs to imobalize the incoming frogs, then spam stuns. Two should do it. The remaining frogs should be taken out with the Solar Gun. It's important to conserve Mk. II ammo for later on. If you're a daredevil, though, go ahead and use it. you can replinish your stores from akiba if you run low. When the frogs stop jumping on the walls, take cover behind the wall JUST BEFORE the doorway, and wait with either the solar gun or mk. II. When the frogs show their heads, pop out and neutralize them, then hide again. this is insanely easy, and you may have 100% health left after it's all said and done. Once the frogs are out of that hallway, go into the... I don't know... lounge area? Just past the bar. Not the kitchen. Enter that area and use the table as cover, taking care not to hit myrel or her boys with the solar gun if you have it out. Same strategy as before, take out one frog, hide, perhaps charge, and duck out again, subduing another. Then you'll want to take out the frogs in the kitchen. This can be annoying with just the solar gun, as it has that nasty habit of destroying bottles instead of frogs... >.>. A smoke grenade will imobalize and maybe stun them if you're lucky, and a few shots with the Mk II ends this part. ONWARD! Let myrel's gang go down the stairs first. There's nothing you can do once the frogs get positioned, except maybe go prone and use the Mk II to go up the stairs and take out the snipers (there is plenty of time for this). When they start to move, just before the part where akiba gets K.O.ed, toss a smoke grenade at the wall that will colapse. Akiba will go unconcious, and you can uniquip your weapon and do that three-move attack, waking him up, and getting him out of harms way. Draw that nice Mk. II and put on Nightvision (after the flashbang) and take out the remaining frogs. Phew! Hard part over. Go to the hallway, and once the cutscene's over head down. Drop a smoke or three where the bulldozer will be, and get out your Mk. II. Why the Mk. II you ask? there's a lot of places for the Solar Gun to get snagged here... a few shots from the Mk. II fixes that, and if you're conservative you can pick up the anesthesia in the next room. Once you clear this area of frogs, you're finished. On to bigger & better things.
 Crescent Meridian
Your goal here is to protect that tank at all costs. This means neutralizing two PMCS that are toating javelins with your Mk. II. This is very hard to explain, but I'll try. The area off to the right of where you are after the tank cutscene is where you need to head. You cannot use the "Solar Gun" very effectively here, save for long-range attacks. Get line-of-sight to the window where the first javelin guy will be, and take him out when he appears. Be quick about it, as the tank will soon obstruct your view. Then, turn your view to the bombed building to your rights rooftop. A PMC will soon be there to rain on your parade. A well-placed Mk. II shot, or a mosin-nagant shot (if there are no enemies in ear reach) will take him down. Then, wait for that tank to work its magic on the baricade up ahead. Crawl over there and neutralize those who get in your way. Congratulations! You cleared Crescent Meridian.