Here is the full list of all 55 Serious Sam VR: The Last Hope achievements.
Complete all level 5 arenas
Complete a level 10 arena
Deploy a dummy decoy
Activate invulnerability
Activate rage
All 5 silver medals
Fire the orbital psi laser
Unleash an army of domestic spiders
Detonate a serious bomb
First platinum medal
First perfect serious
First gold medal
First perfect hard
Activate time stop
Complete a planet without healing
Complete a co-op game
Complete a level 5 arena
Activate serious damage
Deploy a defense turret
All 5 wood medals
All 5 bronze medals
All perfect tourist
All perfect easy
Defeat the Earth giant
Defeat the giant Swamp Hive
Fire the orbital stun field
First perfect normal
Activate money time
Defeat the Shaanti dragon
Use the portable medkit
Step into the arena
First perfect tourist
First perfect easy
Defeat the giant anomaly
Deploy a drone squad
First wood medal
First bronze medal
First silver medal
Defeat the giant mummy
Fire an orbital laser strike
Unlocked a skill
Step into the battlecruiser Saratoga
All 5 gold medals
All 5 platinum medals
All perfect normal
All perfect hard
All perfect serious
Unlocked the entire skill tree
Complete a mission on hard without taking any damage
Complete a level 15 arena
Complete a level 20 arena
Complete all level 10 arenas
Complete all level 15 arenas
Complete all level 20 arenas
Fire an orbital laser storm