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