Here is the full list of all 40 UnMetal achievements.
Have 90 or more bullets at the same time.
Reach level 10.
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.
Break all toilet doors.
Neutralize 5 guards using the slingshot.
Complete "Jerico's Heart".
Complete the catacombs without destroying any cell gates.
Defeat TAKUMA TAKAGASHI without letting him heal himself.
Obtain Robert's photographs.
Destroy 9 mechanical spiders.
Reach level 8.
Heal 20 guards.
Get the maximum experience possible in at least 5 chapters.
Find 15 secrets in the game.
Complete "A Thousand Eyes Are Watching You".
Put 20 guards to sleep.
Complete "Boom Docks".
Craft a Molotov cocktail.
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.
Let SPLASH MIKE destroy all crates and trucks at the barracks.
Complete "Welcome to the Jungle".
Complete "In the Lion's Den".
Reach level 4.
Die while tampering with items from your inventory.
Destroy 5 drones by punching them.
Complete "Something Stinks Really Bad".
Defeat Sewerjunk without damaging it with the Flamethrower.
Kill 5 Human-Piranha-hybrid things with the shredders.
Complete "The Great Escape".
Reach level 2.