Here is the full list of all 18 SiegeVR achievements.
Kill 3 enemies with head shots
Hit 5 or more enemies with one explosive arrow
Shoot down an enemy catapult round
Ring a bell with a flaming chicken
Hit a popup target with a thrown arrow
Achieve a 10-hit atreak during a Gallery match
Score over 50,000 points in any game mode
Shoot 5 targets within 5 seconds in Gallery
Shoot 5 enemies in the knee
Shoot an enemy with an arrow over 50 meters away
Score over 25,000 points
Shoot a bottle out of the air
Get a perfect castle defense bonus
Hit 3 bullseyes in a row in a Gallery match
Kill an enemy with a chicken
Score over 75,000 points in any game mode
Give 10 high-fives
Score over 100,000 points in any game mode