Here is the full list of all 14 Virtuous Western achievements.
Enter the first level of the game
Shoot your first enemy
Shoot an enemy while he is reloading
Make two enemies shoot each other
Smash an enemy with a box
Blow up an enemy
Make an enemy shoot a barrel of TNT
Blow up several barrels of TNT in a row
Collect 3 bullets in the same stage
Blow up more than one enemy with just one dynamite
Shoot down the shotgun enemy
Defeat the boss
Complete all stages
Complete the game in Speedrun mode