F.E.A.R. 2: Project Origin

This is pretty much self explanatory, if youre beaten the game at least once, you will know the harder places and how to deal with them.
Talking about hard mode, its not hard at all, enemies can deal greater damage to you, thats all.My main advice is that you better have collected all reflex injectors on your previous playthroughts, because bullet time in hard mode helps a lot!While playing, dont rush into your enemies, if your bullet time bar is empty, just wait at the corner to fill up, and use it when needed.
As for myself, hardest place was those invisible enemies who attacks you with electricity(few hits and youre dead) so always try to use bullet time on them combined with a shotgun.
Also those fast naked zombie things can be a bit annoying, so as i mentioned before, use bullet time along with a shotgun.
Boss fights are same as on normal, so dont be afraid:)

The infamous "Play The Game On Easy Then Change It To Hard On The Last Checkpoint Of Every Level" trick as featured in many Xbox 360 games also works here.

First and foremost, Hard Difficulty in this game is NOT hard at all. You are an amazing bullet sponge on this difficulty, the first time I played it I legit thought I had forgotten to change the difficulty to hard I was taking so many bullets and not dying. But if you're stuck on a particularly frustrating and badly designed section of the game or just want to breeze through it because you've already spent a hundred plus hours boosting Four Star General and even the mention of FEAR makes you want to vomit, this solution might be for you.

All you have to do is:

-Play through the entire level on Easy until you hit the last checkpoint and the game auto saves. Easy difficulty is basically God Mode
-Die. You can either let enemies kill you or grenade yourself up til dead. (If you are out of enemies and grenades, you can quit out, change the difficulty to Hard in the menu, and then continue from your last save point. The difficulty will now be set to Hard in the game)
-Change difficulty to Hard and then select "Load From Last Save"

The checkpoints are:

Mission 1
After opening the music box Alma was looking at. There are no enemies here so you'll have to use grenades or quit out

Mission 2
After the cutscene with Alma on the swing ends. Plenty of enemies here

Mission 3
You'll be in a hallway and a guy on the radio will talk about a woman and having to save her. Checkpoint hits as you walk towards the door at the end of the hallway. No enemies here

Mission 4
You'll be walking up stairs towards a door while the facility begins to explode. Checkpoint hits near the door, there are no enemies here

Mission 5
After you turn the second valve to fix the elevator platform. This will spawn a Power Armour Unit, but these are very easy by using Shock Grenades to stun them and then filling them full of bullets while they're incapacitated. There's a great platform in the center of the room you can hide behind and they can't hit you if you're crouched right

Mission 6
After defeating the Power Armour, crossing the electrified water, and defeating the two enemies that spawn right after. Stokes will get on the radio complaining about snipers as you approach on open door, checkpoint will trigger shortly after this. You'll have to use grenades or quit out

Mission 7
After you're forced to abandon your beloved Power Armour in the parking garage, you'll have to go into an open door and down a series of stairs. Griffin will radio in, and then Stokes will reply. Around this time you'll push open a door and the checkpoint will trigger. You'll have to use grenades or quit here

Mission 8
After you've defeated the Power Armour and killed your way across the roof of the school, you'll get a checkpoint after re-entering on the upper floor. You'll have to grenade yourself or quit out before turning the nearby valve to shut off the gas

Mission 9
After you use the key card to open the first door you can with it, you'll hit this checkpoint as you enter the door and walk down the stairs (you'll see a "Science Fair" banner directly in front of you). Plenty of enemies after this part to take you out

Mission 10
After you defeat the four cyborg ninja units, you can enter the elevator and press the button to make it go down. This triggers the checkpoint, there will be more enemies waiting for you when the door opens

Mission 11
You'll get to a part where a train runs over two soldiers. From there, kill your way to the nearby area upstairs so you can get on top of the train and jump off to the other side. When your boots hit the ground you'll hit the checkpoint. Depending on who you killed there may be a few soldiers left on the other side of the train, otherwise there is one last soldier hiding at the end of walkway

Mission 12
After you're once again forced to abandon your cherished (wink) Power Armour because it won't fit in a building, you'll walk through the building and exit out on the street. The checkpoint should trigger here, but this one was glitchy for me. I did this level three times and twice it triggered for me on the street when the boss tier Power Armour spawned, so I just ended up doing the entire level on Hard. Again, this game might be the easiest Hard difficulty I've ever seen

Mission 13
When the tram arrives at the Still Island Facility, you'll get your checkpoint. Grenade yourself or quit out

Mission 14
After you've been strapped into the chair and transported to the other world, you have to make it to the same panel you used to activate the chair and push the button again. It'll reset and you'll have to do it again, which gives you the final checkpoint. Plenty of enemies here to kill you.

For the third part of this, I recommend taking the left path and making a mad dash for the button while activating Slo-Mo and using the Laser to cleave every ghost zombie soldier in your path. You want to press that button ASAP because you will die very fast here on Hard.

If you did every last checkpoint on hard, the achievement will unlock as the credits start playing after the... interesting final cut scene.

If the achievement didn't unlock, from the Main Menu select:

-Start
-Mission Select

From here you can scroll through every mission and in the lower right hand corner of the screen it'll tell you if you completed it on Hard or not. It'll also list all the collectibles which is handy if you missed any in a level.