Deus Ex: Human Revolution

Here are some general tips I found to work well completing the game on the hardest difficulty.

1: Save the game after every important event, such as clearing a room or beating a mission

2: Go silent and non lethal. It's easier. Getting into firefights on the hardest difficulty is ridiculous. 2 shots and you're dead. Stay hidden. Try to sneak through areas using air vents and use stealth in general.

3: Upgrade your battery often to enable you to run through enemy strongholds while cloaked. You can sometimes skip entire sections of the game if you have enough battery power to run through them with stealth camo engaged.

4: Upgrade your take-down ability. Being able to take down two enemies with one take down will prove highly useful later in the game.

5: Go everywhere, find everything, do all side missions, and whatever else you can think of to upgrade your character.

First boss: Stay hidden, and shoot him the head when he waits for his weapon to cool down. If you have no weapons, try throwing the gas canisters and explosive barrels at him.

Second boss: stay away from her at all times. Lay a few shots off, and run away. Save the game after every engagement. Try to get her to electrocute herself using the power, just remember to jump to avoid being electrocuted (or upgrade your leg prosthesis to enable surviving the electrical current).

Waiting for the Funicular: I avoided this entire firefight EASILY. Simply barricade the entrances to the room with boxes and vending machines. To be safe, lay gas mines near the barricades just in case they squeeze through (which they probably won't). Now just sit and wait for the funicular happily and safely.

Third boss: This boss fight is incredibly easy. At the start of the fight, run to the left, and as the boss jumps over the wall, knock him out with a take down. This video will show you how:
Forth boss: This is easier than it seems. First take out the turrets with a heavy weapon like the grenade launcher. Then either hack the terminal to disable the pods, or open the hatches and stun the women inside. Sometimes soldiers will come in. Use take downs or gas grenades for quick neutralization. Once the women inside are out cold (or dead), run to the highest point of the map. It's like a little cove. Just look for it and you'll find it. (or upgrade your leg prosthesis to enable surviving the electrical current) It's the only place the electric currents doesn't reach. Stay there crouched and unload bullets on the window protecting Zhao, or just wait for her to break it herself. When she's exposed, take her out however you please. I just spammed her with the lazer rifle. It's actually really easy, just make sure to save frequently.

Adding to the previous solutions, there's a very easy way to kill the final boss, but requires a bit of previous preparation. You must carry a Laser Rifle (you can find one behind Tong in the Harvester Hideout, or another in the room where you fight Jaron Namir).

You will need like 600 ammo for the rifle. It's easy to find some batteries in Panachea, they are located at the beginning of the level over a red crate, and inside the rooms where Taggart and Sarif are.

When the fight with the boss starts, simply activate the cloaking so the turrets don't kill you, get nearer the boss and shoot her through the glass. Don't worry, the laser goes through and damages her. Hold the trigger a few seconds, and it's done. Easy as pie.

Here are some tips for the boss fights because if you go in prepared they're stupidly easy.

First Boss:
Before you walk in try and upgrade a combat rifle/machine pistol and stock up on ammo. Will make it a lot easier not risking yourself to get the ammo.As soon as it starts shoot the explosive barrel next to him.

In 2 corners of the room there are little rooms where the guy won't follow you in, he will stand at the opening. Just cover behind the box on the left and when he throws a grenade run to the other side and repeat. If the grenade lands in between the two bits of cover run outside and just use the cover of the columns. Also make sure your shooting him in the face. If you have any grenades use them as they will help.


Second Boss:
Make sure you get the augment which stops any electrical damage it will make this 20 times easier. It is the 4th upgrade under dermal armour Before you walk into the elevator there is a room to the left with a Heavy Rifle and Ammo. Make sure you take it in with you even if it means dropping a machine pistol or combat rifle. Also if you have any EMP mines bring them.

As soon is it starts just shoot her until she runs away. Then place an EMP mine next to the 2 generators next to you. (If you don't have an EMP mine just shoot the generators when she walks past them. Then just unload heavy rifle in her face. Should have more than enough ammo. There are also more generators around the room. But the augment is key as otherwise you'll take electrical damage when the generator brakes.


Third Boss:
If you have the grenade launcher from Tong's bonus mission then simply shoot him 5/6 times and he should drop literally takes 5 seconds.

If you don't have pre-order bonus mission pack then there is a handy glitch where you can just knock him out using B (video below, courtesy of PowerPyx on YouTube)


Final Boss:
Instead of killing the pod things manually there is a level 5 keypad which deactivates them. Code is 2012. After that simply hide until the glass brakes and then unload on that bitch. There is a platform where the electrical floor charge can't get you. But if you have the augment i recommended for the second boss it should be fine. Just avoid the security bots.

All the bosses up to and including Namir can be stun locked with frag mines. As soon as the action begins hit them directly with said mine and it is plain sailing from there, usually takes about 5/6 mines. If you don't hit them with the 1st mine then I recommend re-starting the last save as it would be easier in the long run.