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