To get the Jetstream achievement, you'll have to beat DL-Story 01 on Revengeance difficulty in one hour or less.
First off on this:
1. If you die and restart, it still counts for your playtime. If you die for 30mins on the first boss, go back to the title menu and start from the beginning because you will regret if you fail from that alone.
2. Most of Sam's charge attacks pack quite a punch - but they'll get you killed on Revengeance. Only use them when you're confident in not getting hit.
3. Counters are your best friend. This goes without saying on Revengeance. To counter an attack you'll have to parry at the last moment (the attack will execute automaticly). Most mobs will jump back before getting countered - but they don't do this on every attack, so pay attention when you want to counter the mob.
4. Sam's taunt is quite useful but can kill you as quickly. You can't counter enemies that are enraged so use this ability carefully (You might end up parrying for 30s in a row).
5. Many of the mission's parts can be skipped by stealthing. That's recommended.

This part is rather easy. You can avoid almost all the enemies on the way.
After starting the game, sprint past the first pair of enemies, turn left (and stay on the upper part of the level), run past the patrolling machine, turn right, pass the guarding npc from below, jump into the upper room and wait there in a corner until your alarm has worn off. Then sprint to the door.

As soon as the door opens, you want to dash forward a little (but don't dash when you're too close to the enemy - they'll hear you!). Pass by his back and jump up on the right, then wait for the 2nd guard to come to the room. Use blade mode to kill him immediately before he can see you.

This battle can be completed within a minute. I recommend not using taunt at all. The thing you want to do is counter his dash attack (the one where he comes in a drilling motion). If you counter that attack, he won't be able to jump back and you'll hit him for 20%.
You might want to throw in a few normal attacks as well inbetween those dashes. A safe moment to hit him is during his 3-hit combo: Block the first attack, evade the second, then double-jump immediately and start a heavy attack mid-air. That will hit him good (and stagger him most of the times) without you taking any risks.
Keep that up until he's dead. Don't lose your cool, just keep it easy.

This one can be stealthed as well. After finishing Bladewolf, immediately run up the stairs on the right and wait for the robot to come. As soon as he turns to go the other way, run above the guy guarding the door and jump down behind him, open the door and walk in. Remember not to sprint otherwise he'll call the alarm!

As soon as you are in (the door closes behind you), start spriting towards the barrel, then sprint to the right next to the door and hide yourself in the barrel. Wait for the robot to pass you, then walk in (with the barrel). You can walk up the stairs immediately without having to worry about the two guards in the room, just remember not to move while the camera is pointing at you.

As soon as you passed the guard on top of the stairs and go inside the hallway, you're safe for this part.

This is one of the tricky parts, in my opinion. Immediately run up to the elevator and start it to save time. As soon as you're done starting it, there will be two light-armored dudes behind you. You want to counter one of them as soon as possible (they will counter your counter, if you counter one your counter can still hit the other guy and take him out). As soon as it's just one person left, I recommend using Dash-LightAttack-Heavy(charged) to throw him up in the air. This is a safe option to deal with the last guard while the small hand-robots are still about. As soon as you're done with the 2nd guard, deal with the small robots. They shouldn't be a problem.

After this the elevator will stop and you'll have to deal with another bunch of enemies. First off, you want to kill the guy on top of the big containers (at best you jump up, wait behind him until he pulls his sword, then use blademode to kill him asap). To deal with the two robots you'll just have to counter (takes concentration and practice) but one successful counter will deal with them immediately.

When you're done with those two encounters you'll have to face the MG

The MG is pretty easy. First thing you want to do is dash to the right (because of his laser), then close in on his left (your right) foot. I recommend using Dash-LightAttack-Heavy(charged) and a mid-air heavy (uncharged) followup. If he attempts to stomp on you, block his attack (it'll cause him to fall over). Repeat this until you've used blade mode twice on EACH leg.
After that, taunt him and block his face attack until you stun him - then hit him hard while he's still stunned and finish him off.

After leaving the room you'll find another stealth-able part. Hide in your barrel and follow the guy on the left of the hallway. Always stay on his back-left and follow him until he stops in front of the door. After standing there for a while, he will head to the right. When he does so, leave your barrel and use the panel as soon as he walked past it. Walk out of the room immediately (because he will look back if you take too long).

After entering the garden, go the the right and hug the house wall (while being in a barrel when you hug it). An enemy will come patrolling. As soon as he passes you, walk straight behind the house. You can put off the barrel there because it's not important anymore for this part. Sprint up the stairs and jump over the roof until you reach the house (the one where you have to slice the walls open).

After passing that house you'll encounter 3 heavier robots. These can be dealt with quickly: Run behind the one that spawns on the very back and wait for all of them to close in. Then counter the first attack that comes. If you're lucky, you'll kill them all with the same counter-attack (meaning you'll be done with the whole thing within 15 seconds).

After killing them, enter the next room.

Run to the right immediately to avoid the guard seeing you as he passes the door. Deal with him just like the first guard you killed: Blade-mode before he can see you. After that head on to the elevator hall.

Plenty of smaller bladewolves will come spawning one after another, including some regular guards and a heavy-armored one that will spawn last.
To deal with all of them easily, run to the last elevator on the right and dash in as soon as it opens. There'll be a bladewolf in there. Don't worry, you might think you're screwed in this room but you're not. Stay in there, spam LightAttack-LightAttack-Heavy(charged) and counter some of the guards' attacks when they get too close. It's really easy. You should be done with all the enemies as soon as the heavily armored guy comes. For this guy, leave the elevator (for more space, ofc). He's not hard to deal with, just give him some charged attacks here and then (he's slow, meaning there's plenty of opportunity to hit him hard).

After you're done with this one, enter the elevator.

Leave the elevator and get the chest on the right immediately. Then hide yourself in the barrel until the big robot passes the door. Go past him ( you can throw your barrel off until you reach the end of the hallway) but be careful about the next robot in the next hallway. Follow this one until he's almost at the second door. Before he reaches the door, hug the wall on the left and wait for him to turn and pass you. Then take off the barrel and interact with the panel.

As soon as you pass the door, sprint to the right. Keep sprinting until you reach the door at the end. It'll say you need an access code. No problem. After the small cutscene is over, sprint back to where you came from (the two hallways with the 2 big robots). The second robot, which you passed last before, is now a light-armored guy. Dash in on him and take him down (another big guy will spawn but ignore this one). Take him down, he'll have the right access code. When you have him down, sprint back - the big guy will ignore you eventually and you'll be able to enter the door that was locked before. Then head to the helicopter platform

Before facing Armstrong you'll have to deal with two helicopters. These are fairly easy. Just watch out for their rockets (which they'll shoot two each as soon as they glow red) and use mid-air heavy(charged) attacks. As soon as they become blue, use blade mode and slice them once to kill them quickly.

This shouldn't take longer than a minute.

Compared to easier difficulties, he'll change his mode on the very first attack. You want to dash at him and hit him just once to trigger his mode-change.

After he's done transforming, taunt IMMEDIATELY. He will always shoot fire at you. You want to taunt->dodge (to cancel taunt animation early) and then sprint around until he's done casting his fireballs. Then dash in on him to damage him. You want to keep him in rage at all times because he will take ridiculously much damage while enraged (and his attacks are more predictable too). Limit your own attacks to LightAttacks to avoid getting hit. You might want to grab a few repair nano thingies mid-fight to allow some mistakes.

If he happens to use his charge-attack and you're right in front of him - stop any attack you want to do and dodge backwards and then sideways immediately - that's the only way to avoid his charge attack while being closeup.

At 50%, he'll do his regular transformation (although nothing changes for revengance players). When he throws the choppers at you, cut 2 or 3, then spam dodge after blade mode to avoid incoming fireballs.
There's going to be a checkpoint at this point, so any mistakes you do after this one won't be as bad.

Taunt him again immediately. He will always use his charge-attack which you have to evade a LOT. Don't let your guard down, you better evade once too much than get hit by him (if you're unlucky, he might just hit you for 200-300% dmg before you can stand up again).
Basicly it's the same like before 50%, just take him down while having him in rage. It's easy that way.

After killing Armstrong you're done with DL-Story 01. I managed to get the achievement on my second attempt with 31min playtime (including dying here and there).

It's not very hard, you just have to focus on countering (except for Armstrong, you better evade that guy).