Here is the full list of all 26 Serious Sam VR: The First Encounter achievements.
Frag a total of 100 players.
Win a versus match.
Leap into the unknown on Luxor.
Complete the game in single player on unmodified serious difficulty.
Pierce at least 10 enemies with a single cannonball.
Find at least 10 secrets in single player.
Kill 300 Enemies with the Minigun.
Complete the Metropolis level in single player on unmodified serious difficulty.
Complete any level in co-op.
Complete a level in co-op with blood option set to hippy.
Complete the game in co-op on unmodified serious difficulty.
Complete the game.
Complete the game in single player by beating the estimated time on each level.
Trigger Ugh-Zan's regeneration.
Kill 100 Enemies with the Cannon.
Kill 150 Enemies with the Rocket Launcher.
Defeat the Lava Golem boss.
Kill 20 enemies with the Minigun without releasing the trigger.
Kill 250 Enemies with a shotgun.
Kill 200 Enemies with the Thompson Submachine gun.
Obtain the Water Element.
Obtain the Fire Element.
Obtain the Earth Element.
Pull out a single Colt and immediately deliver a killing shot.
Obtain the Air Element.
Complete any level in single player.