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