Hard difficulty is an interesting middle ground between Normal and Extreme, borrowing elements from both.

Overall, you will be eating many rations during this run. Make sure to grab the ration at the forklift in the Dock.

Prozac skip on the Docks is not possible because there are no throwable items

You cannot pick up the M9 until you blow up the northwest wall in the Armory after the Cell fight.

On the Helipad, pick up the chaff at the spotlight, move left, then roll into the vent guard after being shot twice.

In the Tank Hangar, take the same line as in Extreme. You do not need to wait for the bottom guard to pass, as long as you R mash in the vent.

Grab the SOCOM to start, turn around, and fire at the guard closest to you to give the other guards an ! delay. These guards are more aggressive than the lower difficulty guards.

While unconfirmed through hard testing, it overall seems worthwhile blowing up the northwest wall in the Armory for the M9.

You can skip picking up the chaff grenades in Canyon, but you cannot takes the Very Easy/Easy line. Thus, you can save some frames by dodging the Chaff and going upright early.

Remember to lean dodge in FPV at the Tank if your ration count is low.

In Nuke Bldg 1F, hug the bottom of the missiles after performing the door skip. Remember to toss a chaff grenade after performing the door skip.

The balcony guard will not get in your way, allowing you to freely roll up the stairs, unlike Normal.

Dogs can hear you shoot, enabling the consistent cave return to pick up the PSG1-T.

When returning through the canyon, hug the left side, and M9 autoaim TPV shoot the guard beyond the Tank twice.

Hind-D operates like on Extreme, meaning bad luck is not as annoying as on lower difficulties.

Raven spawns NW of you. Go up a row, hug the bottom crate to attack him.

There are multiple ways to approach the Underground Base (Rex's Lair).

Fire the SOCOM in TPV once at the first guard to stun him, then roll into him to knock him over the edge.

Fire the M9 twice at the top guard with autoaim TPV. You can roll after the first shot, get a damage boost, then time your second shot so he falls asleep by the wall.

After the PAL scene, switch to the SOCOM, go into FPV, and autoaim to the lower guard and spam for a crotch shot. This will remove all guards.

Refer to Normal for everything else.