Here is the full list of all 40 UnMetal achievements.
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.
Defeat Sewerjunk without damaging it with the Flamethrower.
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.
Reach level 10.
Have 90 or more bullets at the same time.
Obtain Robert's photographs.
Destroy 9 mechanical spiders.
Heal 20 guards.
Get the maximum experience possible in at least 5 chapters.
Complete "A Thousand Eyes Are Watching You".
Find 15 secrets in the game.
Complete "Boom Docks".
Reach level 8.
Put 20 guards to sleep.
Obtain 5 potties.
Complete "Engineering Problems".
Defeat HUGEEL firing just 6 torpedoes.
Destroy 5 crates with the explosion of a single grenade.
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".
Die while tampering with items from your inventory.
Destroy 5 drones by punching them.
Reach level 4.
Neutralize 5 guards using the slingshot.
Craft a Molotov cocktail.
Complete "Something Stinks Really Bad".
Kill 5 Human-Piranha-hybrid things with the shredders.
Complete "The Great Escape".
Reach level 2.