I would just like to quickly shoutout Duckest, they pointed out some potential issues and came up with the idea of breakable helmets, which also resulted in motivating me to recheck that the guide still holds up.

Note: while the guide is technically finished, there is a thing or two I'd like to elaborate on.

It wouldn't be a comprehensive guide without mentioning other guides.

These are some good guides that I would also recommend checking out, this guide mainly focuses on mechanics.
Xp and Kill grinding
Stealthing all maps (Note: outdated, doesn't include black diamond casino or mansion)
Hidden Achievements (Spoilers!)

I couldn't find a guide on stealthing the new maps, so I'll quickly cover that here.

YOU WILL NEED:

• Lockpick
  
• Suppressed pistol (stock will do just fine)

STEP 1:
Kill the booth guard and disable the alarm. The way I would recommend doing this is by first shooting the camera (on the weightroom overlooking the front area) then the guard. For cleanup, check his phone in at the spot in the booth and then go drag his body in.
STEP 2:
Lockpick in the side door. Be careful of the camera (you can look at it safely through the glass).
STEP 3:
Retrieve the security card from the dresser in the sideroom and watch out for the hallway guard (alternatively his belt has one too). Don't get caught by the camera and once you've got the card, go to the basement (watching out for the cam and frontdoor guard) and "disable" security.
STEP 4:
Lockpick into the other sideroom. There you will find the basement keycard (I recommend throwing it down to the basement) and a check in point. Kill hallway guard when the time is right (you can try breaking some of the siderooms glass to lure him over and do the check-in). After that crash the party, tie everyone up, and kill the owner.
STEP 5:
Bring the owners body down to the basement. Be careful not to be seen by frontdoor guard, even for a split second, as guards notice bodies instantly. You can make sure that doesn't happen by waiting until he starts walking off into the kitchen. Then open the garage door with the keycard, and disable the lazers with the owners handprint.
This is the only image I took of this, sadly.
WRAPPING IT UP
Lift up the car with the button (I recommend getting on the platform yourself, right in front of the car). Then open the garage door with the next button. Then get the hook from the green truck's trailer (not the bed) and attach it to the supercar's front bumper. Wait for it to get dragged on over there, and depart.


I don't have any paid maps, but a little bit of looking and I found a video.
Credit Goes to @BakedBreadGaming, hopefully by linking it this way they get all the views they deserve.

You could also look up more videos yourself.

Primaries - These weapons are to be used if the heist ends up going loud.
Secondaries - These weapons should have silencers on them and are only to be used if the heist is stealth.
Tools - Lockpicks, drills, whatever. Technically you don't need to spend any money on better tools, but it will make your life far easier.

Notes:

See section 5B for more info on helmet breaking and the like.

There is no tactical reason to have a stealth loadout for a rifle, or a loud loadout for a pistol.
The only reason you would do this is if you want to mess around, in which case all power to you.
This guide is about what I believe to be most effective though, so I won't cover that.

Maximum accuracy / minimum recoil in the weapons sections is done with a flash hider for primaries and a suppressor for pistols.

Stats:

• Damage: 35
  
• Helmet braking: 5.4@2
  
• Dps: 379
  
• Capacity: 30/20/40/60/80
  
• Damage per mag: 1050 to 2800
  
• Max accuracy: 104.3
  
• Minimum recoil: 16.3

RECOMMENDATION:
If you're a new player, stick with this and don't bother with other weapons until you level up enough to consider them. Tools (and better mags for this gun) will be a more effective use for your money.

Stats:

• Damage: 30
  
• Helmet breaking: 7@2
  
• Dps: 425
  
• Capacity: 25/40/50
  
• Damage per mag: 750 to 1500
  
• Max accuracy: 121.7
  
• Minimum recoil: 13.1

RECOMMENDATION:
It's base stats are not impressive, and it's low capacity might leave you out in the open needing to reload, but once you've got enough for the basic extended mag upgrade, this gun is unironically GOATED if you can hit headshots. This thing can break helmets incredibly quickly (2nd best helmet breaking in the game), allowing you to
drop SWATS stupid fast. (in just over a quarter of a second)

Stats:

• Damage: 45
  
• Helmet breaking: 5@2
  
• Dps: 450
  
• Capacity: 30/20/40/50
  
• Damage per mag: 1350 to 2250
  
• Max accuracy: 86.9
  
• Minimum recoil: 26.1

RECOMMENDATION:
This weapon does deal more damage than the CX-9 and is also better out of the box (though the recoil is a little high). I'm not sure why I gave it such a bad recommendation previously, but it could be because the CX-9 is actually better if you can hit headshots.


Stats:

• Damage: 25
  
• Dps: 25 - 250
  
• Capacity: 7/10
  
• Damage per mag: 175/1750 to 250/2500
  
• Pellets: 10
  
• Minimum recoil: 78.2
  
• Semi - Automatic

RECOMMENDATION:
I really wouldn't recommend this. Sure, it deals up to 250 damage instantly, but unless you can't keep your gun on a target, that doesn't matter much and only works out to 250 dps at best. This is absolutely pitiful. For reference, a unmodified KX-UPP (the starting pistol) can do 245 dps.

Stats:

• Damage: 80
  
• Helmet breaking: 5.8@1
  
• Dps: 466
  
• Capacity: 10/20
  
• Damage per mag: 800 to 1600
  
• Max accuracy: 144.2
  
• Minimum recoil: 30.6
  
• Semi - Automatic

RECOMMENDATION:
Just don't. Not in early game at least. Its damage per mag is abysmal and realistically you can't reach it's maximum firerate due to lack of input buffering.

Stats:

• Damage: 45
  
• Helmet breaking: 5.4@2
  
• Dps: 487
  
• Capacity: 30/45/55
  
• Damage per mag: 1350 to 2475
  
• Max accuracy: 121.7
  
• Minimum recoil: 13.1

RECOMMENDATION:
The CX-9 is better at helmet breaking, but realistically this gun's higher dps could help if you don't hit 100% of your headshots, or the higher damage per mag could help with juggernauts.

Stats:

• Damage: 50
  
• Helmet breaking: 4.5@2
  
• Dps: 458
  
• Capacity: 30/20/40
  
• Damage per mag: 1500 to 2000
  
• Max accuracy: 132.1
  
• Minimum recoil: 16.3

RECOMMENDATION:
This one's great. Capacity is a little low though. Get it if you've already got heavy armor.
Ummm.... the SP5 is better in the new update?

Stats:

• Damage: 48
  
• Helmet breaking: 5@2
  
• Dps: 480
  
• Capacity: 30/20/40/60/80
  
• Damage per mag: 1440 to 3840
  
• Max accuracy: 139
  
• Minimum recoil: 16.3

RECOMMENDATION:
While worse than the CX-9 at helmet breaking, the high max capacity can make up for it.

Stats:

• Damage: 40
  
• Helmet breaking: 6.2@2
  
• Dps: 500
  
• Capacity: 30/20/40/60/80
  
• Damage per mag: 1200 to 3200
  
• Max accuracy: 116.5
  
• Minimum recoil: 14.4

RECOMMENDATION:
This is technically better than the TACR-H, having the 3rd best helmet breaking. I don't immediately recommend it though because the TACR-H works just fine and I remember this being pretty pricey.

Stats:

• Damage: 20
  
• Dps: 100 - 1000
  
• Capacity: 10/13
  
• Damage per mag: 200/2000 to 260/2600
  
• Pellets: 10
  
• Minimum recoil: 78.2

RECOMMENDATION:
This actually isn't terrible! It also melts juggernauts so it's got that going for it.

Stats:

• Damage: 40
  
• Helmet breaking: 6.2@2 (if you can hit the headshots)
  
• Dps: 500
  
• Capacity: 100
  
• Damage per mag: 4000
  
• Max accuracy: 51.5
  
• Minimum recoil: 40.8

RECOMMENDATION:
I mean.. It's not bad. It just has bad accuracy. Everything else is actually pretty good. That doesn't mean I can recommend it though.

Stats:

• Damage: 85
  
• Helmet breaking: 7.5@1
  
• Dps: 637
  
• Capacity: 15/25
  
• Damage per mag: 1275 to 2125
  
• Max accuracy: 135.2
  
• Minimum recoil: 30.6

RECOMMENDATION:
Now while this is basically the SPR-12 #2, I actually quite like this gun. Its damage per mag is still pretty bad, but the lack of buffering on inputs is much less noticeable with the higher firerate, and the crazy potential DPS just about makes up for all that.

Stats:

• Damage: 55
  
• Helmet breaking: 5.4@2
  
• Dps: 595
  
• Capacity: 35/25/45/65/85
  
• Damage per mag: 1925 to 4675
  
• Max accuracy: 121.7
  
• Minimum recoil: 22.8

RECOMMENDATION:
This is just flat out the best rifle in the game. 2nd best dps (without a crazy gap), and the damage per mag plus the accuracy more than makes up for it. The only thing it doesn't have going for it is helmet breaking.

RECOMMENDATION:
Just use this if you can hit headshots. Any pistol can instakill a guard if you hit a headshot. Heck, even if you can't, It has the 2nd highest firerate for any pistol (the double barrel does NOT count) and good damage!

RECOMMENDATION:
This has a higher firerate, more capacity and more damage, but less accuracy when fully upgraded.

RECOMMENDATION:
This thing deals pretty high damage and is pretty upgradable. I guess you could use it if you wanna hit bodyshots.

RECOMMENDATION:
This is basically a worse 11A1. Unless you max out last stand, in which case you'll deal double damage for the last 5 of your 6 shots, making it a pretty fun combo and able to 1 hit bodyshot guards.

RECOMMENDATION:
Full auto pistol. Get if you hate accuracy.

RECOMMENDATION:
45.ACP go brrrr
Gud gun 👍

Stats:

• Dps: 5000 - 50000 (With at least T2 last stand, 10000 - 100000)
  
• Capacity: 2
  
• Pellets: 10
  
• Minimum recoil: 200
  
• Consider: if you want to have some fun

RECOMMENDATION:


Note:
It really does not matter which secondary you choose if you're using them for stealth (excluding the sawed off because there are no attachment options for it). For new players, just don't bother buying any others and get an extended mag for the KX-UPP if you really need it. If you can't hit shots to save your life, maybe consider getting the UP92 or UP99.

It sucks, but it works.
It sucks way less, and is something you should definitely get as soon as possible.
It lets you pick doors in seconds. A must have for the late game.
Not necessary, but lets you skip getting keycards (and with an autoclicker / spam clicking can become super fast).
Kinda a letdown. It does blind cameras, but only while you point it at them. At that point, just dodge them normally. Pretty niche.
Super slow, but technically does its job.
Like the advanced lockpick, this thing is a must have. Get it as soon as possible.
Angle grinder on crack. Very good, but by the time you can get it, you should be able to stealth all the maps.
Lets you break in some doors. Kinda niche, wouldn't recommend buying for the average player. If you wanna speedrun though...
It's pretty nice to have on a loud mission, but very costly and not very fast. You don't need it, but if you have at least medium (ideally heavy) armor, you could try going for it. If you do use it, always place it on the top drill point of small vault doors, that way there's a chance it could fall to the bottom one and go through that as well.
Fittingly, you'll see 4 bricks in its spot on the rack. Attach them to whatever lock stands in your way, shoot them, and odds are the way will be cleared.

Apperance - Skin tone, mask, clothes. Mostly pointless, but is the category armor resides in, which is certainly worth talking about.
Skills - Not necessary, but like better tools, better skills will make your life easier.


Notes:

You can research up to 3 skills at once.

XP gain progresses research proportional to how much you got. Ideally you should have at least 1 thing researching at all times to make the most use of that.

It is important that you completely buy out all the paid cosmetics, because if you don't have at least 69 paid cosmetics equipped at once and if you don't there is a 2 billion% chance that whenever a guard spots you, he'll shout "HE GOT THEM FAKE JAYS" and 420 gazillion juggernauts will spawn on your location instantly crashing your computer.

Jokes aside, it doesn't really matter what cosmetics your wear. What does matter however, is your armor.
I'd pretty much recommend rushing light armor after you get an extended mag for your LC4 and maybe an advanced lockpick (unless you suck really bad), but medium armor is far more reliable, and heavy armor makes you the bullet sponge of all time. Also, as far as I can tell, there is literally no tradeoff to armor. No speed penalty. Nothing.

Consider skills based on the recommendation, and what you feel you currently need.
SCAVENGER:
This skill is pretty useful for not running out of ammo. It makes things a lot smoother. Would recommend.
SHARPSHOOTER:
I guess it's nice, but only for late - game. The difference it makes is small. Would not recommend.
DEADLY AIM:
Again, tiny difference. Even when fully upgraded, 15% is only really something on the more damaging guns. Would not recommend early.
Helmets are NOT affected by the deadly aim skill.
LAST STAND:
It's just on the last 5 bullets when fully upgraded. Might be somewhat useful on stealth with pistols, but there's better things to spend your money on. Would not recommend.
SPEEDLOADER:
Very convenient to have. Would recommend.
HEALING TOUCH:
Should in theory be useful, but I think it's bugged, and only visually makes the revive bar go quicker. If the bar finishes but they're not back up, keep holding the button down. Wouldn't currently recommend.
TOUGH SKIN:
Useful. Literally just more health. Would recommend.
HERO:
Less damage while reviving, would recommend if SWAT keeps stopping you from reviving your friends. (assuming it works)
REGENERATIVE:
Direct buff. A fine choice if you need it.
TANK:
Extra armor. Might recommend, though you could always try to play it smarter in combat, and the increase is kinda small at lower levels.
ARMORED FEET
Interceptors annoy you? Get this. Might recommend if you've got money and time.
DRILL SAFETY:
Really helps when going loud. Would recommend if you like doing that.
SABOTEUR:
Kinda meh. If going loud is all you do, then I might recommend it.
CAMERA DODGER:
Ehh... Cameras are pretty easy to dodge, might recommend if you're having trouble with them.
GUARD DODGER:
Another kinda meh one. Guards are slightly more unpredictable than cameras, but it's another might recommend.
COMMUNICATION DELAY:
This one is really convenient to have. Would recommend, get at least tier 1.
COMPUTER SCIENCE:
Direct buff to hacking speed, reduces carpal tunnel. Would recommend if you intend to be hacking pads in your heists, otherwise it's useless.

While mostly covered in the grinding XP guide I pointed you to, it doesn't cover cash grinding and there's also another map that you can grind XP on, the jewelry store, which is great for the freshest of fresh installs.
This is because the jewelry cases all have locks on them.

YOU WILL NEED:

• Suppressed pistol (literally the stock one will do)
  
• Some skill

For grinding cash, the best free map currently seems to be mansion. Now while if you do maps like liberty hawk bank fast enough it can be just as good or better, that usually requires a hacking tool. My method is more reasonable, because it allows you to hit around 3.6 million per hour with just the starting guns and no tools! (Special thanks to Whoa who made a guide also showing how to money farm on mansion, but the route was unoptimized)
This route is pretty tricky and may require some practice, but once you have it down, it can get very consistent. Also sorry in advance for the low quality gifs, steam doesn't allow anything over 2 megabytes, and I didn't want like 20 gifs.

Grab your weapons, head to the booth, open the door and hit the alarm switch. You can also try to do what I did, grabbing the hook and throwing it over, which will make a later part faster but will also make everything more precise, so I wouldn't recommend it if you're just starting to learn the route.

Immediately after hitting the alarm, run towards the weight room and the house. Shoot the glass in as shown (don't forget the extra 2 panels!). I would recommend reloading after that if your pistol has a low capacity.

Run upstairs, and shoot the keycard siderooms glass in and the camera down (guards won't notice the cam because it's unreachable). Careful not to shoot the glass in too soon, or else the hallway guard might not be far enough to not notice the sound. Around where I did it is good. To get through, crouch and vault through.

Go through the 2 windows you broke previously. Make sure when going through the bottom one, you start at the left end so you don't bonk your head but also at an angle so that you stay under the top stairs and out of sight of the camera. Once you're down there, shoot down the camera watching the pad, and quickly use the keycard to open the doors before the guard reaches you and raises the alarm.

Now, there is a problem. There is a lazer grid that will trigger the alarm if you go through it between you and the goal, so in order to reach the car we will do a common speedrunner strat called "Not Caring". Run straight through, hit the lift button, get on, open the garage door and tow the car (this is what throwing the hook may have made faster). While you're at it, shoot that window out. It's a surprise tool that'll help us later.

After shooting the window out, go to the van, retrieve the duffel bag, take care of any police that may have come to stop you, and go back in.

You've got about a little over 1 minute before the car has finished towing, and you're supposed to hit the end heist button. Steal the stuff as shown, and remember how to get through that one window.

Once you've got everything from the safe, get out of the keycard sideroom.
Remember that surprise tool? That one window you broke on your way to the van is in the hall. It's the exact same as the ones of the keycard sideroom. Crouch, vault through, and land on the overhang. Run across towards your van, drop down off the end of it, and hold down the fort in the van until the car is just about to finish towing.

Once the car is about to finish (or has finished if you mistimed things), go to the button and start spamming it to finish the heist as soon as it does finish towing.

If everything went right, you should have 150K after just around 2:20 - 2:30!
If you have any friends at all, you could have them go get the hook instead of throwing it over, making things quicker without making the heist much more difficult.

CAMERAS
Whenever you shoot a camera, the nearest guard will immediately run to it.
This will not happen if the camera is unreachable (guards can't pathfind to it).

In some cases, you can also make the distracted guard run to another cam if you shoot it.
STRANGE SOUNDS
Similar to cameras, whenever a strange sound occurs such as glass breaking, a door being bashed down, or using a loud tool such as a drill, the nearest guard in range will go to investigate.
Now what constitutes as in range I'm not quite sure, but generally ramming in doors and drilling seem to have a larger (possibly infinite) range than breaking glass (unconfirmed).
UNARMED PLAYERS
Whenever a guard or camera spots a unarmed player, nothing will happen, unless they are in a restricted area. If they are in a white restricted area, a camera will alert the nearest guard, who will walk on over to you. A guard will just immediately do so. When the guard reaches you, a yellow circle will appear around them. This is the escort zone. If you do not stay in it, then the heist will go loud. To avoid this, follow the guard until they finish escorting you outside, and the circle disappears. If the player is in a red restricted area, the guard will pretty much behave exactly the same as if the player was armed.

VAULTING
Ok, this isn't technical at all, just press space when up against a ledge, and you'll hop over.
There are some weird spots you can exploit it though.
You can vault through this gap in the bars in orbital bank.
As shown before, you can vault through this type of window when crouched.
LEDGES
Due to the player collider being a capsule, you fall off a ledge after you've visibly left it. This necessitates getting used to.
If you want to approach a ledge quickly, but not fall far from it, simply release sprint just before going off.
QUICKSTEALING
I'm not quite sure if this has an offical name, I just decided to come up with one. You might have seen traces of this earlier in the guide, but this'll go into it in more depth.

As shown here, if you just hold an item and then drop it without moving your arm, it'll drop straight down. If you position a duffel bag / cart below that spot, you can spam click to transfer lots of items, very quickly. It will take some time to learn, but is pretty easy to do so, and essential to robbing well.


This is short enough that I could afford more pixels to show it in more detail, but if the object is slightly off from where you'll drop it, you can move your arm and release while in motion to impart some movement on the item. This is only a little bit slower and more versatile, but harder to learn than a normal speed steal.
The humble cart. This thing does not like being used, but in the right hands can speed things up a lot. Utilizing it well essentially boils down to 4 things.

• Loading
  
• Nosing & Threading
  
• HANDS OFF! (In multiplayer)

First off, loading. It's fairly simple, just try to stack stuff up more towards the handle, but not too much so that you can nose it. If you don't have to nose it (like on orbital bank), you can pretty much ignore this (just keep stuff from sticking off the sides so you can thread it).

Then there's nosing, another thing I had to make up a name for. Here you can see our poor robber is having trouble fitting his cart out the door. Fortunately for him, he remembered that he lives in a 3 - dimensional space, turns the cart sideways and has about half the front obstructed. He then turns perpendicular to it, and because of the way he's applying force, it twists so that it's goes on its side with the tall handle poking out. He then wiggles it a bit, and it pops right out. This will make getting through doors a whole lot faster for you.

Now while the small vault door is slightly too thin to fit the cart normally, normal doors are actually just barely wide enough to fit it.
If you're precise and have it pretty much perfectly perpendicular to the door, it can go through. Mastering Threading and Nosing can make using the cart much less annoying.

Because this game is coded... "creatively", for some reason your hand will collide with the cart when in multiplayer. This can cause it to explode and if it does, any items on it will be sent all over the place. Just don't bump the cart with your hand, and make sure it comes to a complete stop before letting go of it.

All units will get one tapped by headshots, but some have helmets that will block headshots until being destroyed. Note that some damage will still go through, somewhere around 50%.
• Standard helmet: 60 HP (Uncertainty 57 - 60)
  
• Juggernaut helmet: ~2000 HP?
  
  
• Civilian: 1 HP
  (Uncertainty: 1 - 27 |No helmet|)
• Guard: 100 HP
  (Uncertainty: 97 - 100 |No helmet|)
• Policeman: 100 HP
  (Uncertainty: 97 - 100 |No helmet|)
• Elite Policeman: 100 HP
  (Uncertainty: 97 - 100 |Standard helmet|)
• S.W.A.T Grunt: 125 HP
  (Uncertainty: 120 - 126 |Standard helmet|)
• Powerbox Defuser: 200 HP
  (Uncertainty: 195 - 218 |No helmet|)
• Juggernaut: 2500 HP
  (Uncertainty: 2481 - 2520 |data probably bad, juggernaut helmet|)
• Interceptor: 200 HP
  (Uncertainty: 190 - 216 |No helmet|)
• Shield Guys: 250 HP
  (Uncertainty: 225 - 256 |Probably standard helmet|)
  Standard and blinding may have different HP values, though I find that unlikely.

These are my best guesses based on how many shots it takes to kill them for different guns. Uncertainty, if any, will be provided.

Helmet breaking stat is something I made: (helmets per second)@(shots to break 1 helmet).

• Bullets actually come out of the barrel of your guns!
  
• Your weapons start with 5 mags of reserve ammo
  
• You can hold up to 6 mags of reserve ammo

While this guide is intended to show you the best ways of going about stuff, One - Armed Robber is a game and not a movie. There are other ways to play it. If you think this way of doing it is sucking the fun out of it, just don't play it like this then. Go nuts. Slap a flash hider on a UP-92 and humiliate all the S.W.A.T units. Waste your money on a SPR-12, slap a scope on it, and become a sniper. Just because I say you shouldn't bother with a stealth loadout on a rifle, doesn't mean you can't.

GUIDE STATS:

• Over 6 days of on and off work spent.
  
• Over 102 images (gifs included) produced for this.
  
• Over 2 words!

And finally:
Don't forget to like and subscribe or whatever
Maybe give some awards if you think I put effort into this.
Any critique of this is appreciated.
I mean, if joke guides can get some, maybe this can get at least one?
UPDATE: It did get one :D first award I ever got on steam as far as I'm aware.