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