Here is the full list of all 23 Serious Sam 3 VR: BFE achievements.
Kill 20 enemies with the Minigun without releasing the trigger.
Kill a Witch-Bride of Achriman.
Decipher an Egyptian text.
Kill 5 Cave Demons while they're in air.
Kill an enemy using the Mutilator.
Solve the riddle of the Sphynx.
Defeat the spaceship.
Secure the bird.
Kill at least 5 headless kamikazes in one explosion.
Rescue professor Stein. So to say.
Complete any level in single player.
Complete any level in cooperative with at least 2 players.
Smash 20 Kleers with the Sledgehammer.
Power up the Timelock.
Start the car.
Find Sam's classic outfit
Awake the Guardian of Time.
Gib 20 enemies from close range with a shotgun.
Blow a Major Biomechanoid into pieces.
Use the Mutilator to surf after a Werebull.
Find at least 10 secrets in single player.
Complete the game in single player on unmodified serious difficulty.
Complete the game in single player in the estimated time on each level.