Here is the full list of all 30 Molten Armor achievements.
Click Start button in main menu
Complete tutorial without skipping
Defeat train boss in a fast way
Destroy caravan among frenemies
All endings
Lose to enemy general
Defeat "the last limit" boss
Defeat "ride of the valkyries" boss
Defeat "in the ashes of the enemy" boss
Defeat "coursed beast" boss
Smell hell completed
Defeat 1000 enemies on shooting range
Meteostation - destroy all reactors
Activate ambush too early
All heroes joined
Point at a skeleton at sand trenches
Point at something weird in frozen harbor
Complete any story level on hardcore difficulty
Complete any story level on medium difficulty
Complete any story level on story mode difficulty
Complete the "chalk and cheese"
Pick any option at the end of "sea devil"
Complete "smell hell" with no damage
Skip tutorial
Destroy boss in level 1
Start level "Oasis of serenity"
Start level "Meteostation"
Start level "Crouching tiger"
Start level "Abuser"