Here is the full list of all 12 Masked Shooters 2 achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Death bringer
Killing for fun
Win a round with at least 25 kills
Win a round without being killed
Win one match
Survive for 2 minutes, without using or changing your weapon
Eliminate at least 5 enemies in a round, with a pistol
Eliminate at least 4 enemies in a single round, with a rifle
Eliminate at least 6 enemies in a single round, with rpg
Getting a grasp of war
Dying
Making a first kill