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