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