Here is the full list of all 40 UnMetal achievements.
Destroy 9 mechanical spiders.
Put 20 guards to sleep.
Complete "A Thousand Eyes Are Watching You".
Complete "Boom Docks".
Reach level 8.
Complete "Engineering Problems".
Defeat HUGEEL firing just 6 torpedoes.
Complete "The Barracks".
Reach level 6.
Complete "Welcome to the Jungle".
Complete "In the Lion's Den".
Die while tampering with items from your inventory.
Reach level 4.
Complete "Something Stinks Really Bad".
Craft a Molotov cocktail.
Complete "The Great Escape".
Reach level 2.
Complete "Jerico's Heart".
Finish the game.
Reach level 10.
Obtain Robert's photographs.
Finish the game without using a potty.
Neutralize 5 guards using the slingshot.
Heal 20 guards.
Destroy 5 drones by punching them.
Destroy General X's robo-tank without using electromagnetic grenades.
Obtain 5 potties.
Kill 5 Human-Piranha-hybrid things with the shredders.
Destroy 5 trucks in the barracks north parking lot before SPLASH MIKE does with his tank.
Complete the catacombs without destroying any cell gates.
Have 90 or more bullets at the same time.
Destroy 5 crates with the explosion of a single grenade.
Find 15 secrets in the game.
Defeat Sewerjunk without damaging it with the Flamethrower.
Defeat TAKUMA TAKAGASHI without letting him heal himself.
Break all toilet doors.
Let SPLASH MIKE destroy all crates and trucks at the barracks.
Reach the ground floor in less than a minute when rushing to save the doctor.
Finish the game on hard difficulty.
Get the maximum experience possible in at least 5 chapters.