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