Here is the full list of all 137 Putrefaction 2: Void Walker achievements.
Achieve godlike rank in timed survival
Achieve unstoppable rank in timed survival
Achieve deathbringer rank in timed survival
Achieve veteran rank in timed survival
Complete main campaign on hard difficulty
Complete main campaign on extreme difficulty
Complete eighth level on hard difficulty
Complete eighth level on extreme difficulty
Complete seventh level on extreme difficulty
Complete seventh level on hard difficulty
Complete sixth level on hard difficulty
Complete sixth level on extreme difficulty
Destroy 50 energy balls with pistol in the boss fight
Complete fifth level on hard difficulty
Complete fifth level on extreme difficulty
Complete fourth level on hard difficulty
Complete fourth level on extreme difficulty
Complete third level on hard difficulty
Complete third level on extreme difficulty
Complete second level on extreme difficulty
Complete second level on hard difficulty
Complete first level on hard difficulty
Complete first level on extreme difficulty
Achieve experienced rank in timed survival
Achieve fighter rank in timed survival
Achieve apprentice rank in timed survival
Complete wave 50 in survival
Complete wave 49 in survival
Complete wave 48 in survival
Complete wave 46 in survival
Complete wave 47 in survival
Complete wave 45 in survival
Complete wave 44 in survival
Complete wave 43 in survival
Complete wave 42 in survival
Complete wave 41 in survival
Complete wave 40 in survival
Complete wave 38 in survival
Complete wave 36 in survival
Complete wave 34 in survival
Complete wave 32 in survival
Complete wave 30 in survival
Complete wave 27 in survival
Complete wave 25 in survival
Complete wave 22 in survival
Complete wave 20 in survival
Complete wave 17 in survival
Complete wave 15 in survival
Complete wave 12 in survival
Complete wave 10 in survival
Complete wave 6 in survival
Complete wave 3 in survival
Complete wave 1 in survival
Achieve novice rank in timed survival
Complete main campaign on any difficulty
Upgrade player energy to maximum
Upgrade player ammo capacity to maximum
Find thirty sixth secret
Find all secrets on level 8
Kill all enemies on level 8
Complete eighth level
Find thirty fourth secret
Find thirty third secret
Upgrade player armor to maximum
Kill all enemies on level 7
Find all secrets on level 7
Complete seventh level
Find thirty second secret
Find thirty first secret
Find thirtieth secret
Find twenty ninth secret
Kill all enemies on level 6
Find all secrets on level 6
Complete sixth level
Defeat second boss
Find twenty eighth secret
Find twenty seventh secret
Find twenty sixth secret
Find twenty fifth secret
Find twenty fourth secret
Complete fifth level of the campaign
Find all secrets on level 5
Kill all enemies on level 5
Find twenty third secret
Pick up grenade launcher
Find twenty second secret
Deal with jetpack squad
Find twenty first secret
Find twentieth secret
Find nineteenth secret
Upgrade player speed to maximum
Complete fourth level of the campaign
Find all secrets on level 4
Kill all enemies on level 4
Find eighteenth secret
Defeat enemies near the bunker entrance
Find seventeenth secret
Find fifteenth secret
Pick up mp40
Find sixteenth secret
Find fourteenth secret
Complete third level of campaign
Find all secrets on level 3
Kill all enemies on level 3
Kill the rock boss
Kill all enemies in the blood chamber
Deal with guards of the green rune
Find thirteenth secret
Defeat group of enemies at sector 1
Kill 4 enemies with 1 dynamite explosion
Find twelfth secret
Upgrade player health to maximum
Find eleventh secret
Find tenth secret
Complete second level of campaign
Find all secrets on level 2
Kill all enemies on level 2
Defeat last group of enemies before the temple
Find ninth secret
Find eighth secret
Find seventh secret
Find sixth secret
Kill enemies near the town center
Pick up dynamite
Find fifth secret
Complete first level of campaign
Find all secrets on level 1
Kill all enemies on level 1
Deal with guys from cave near the road
Find second secret
Find fourth secret
Defeat tribes after picking shotgun
Kill 2 enemies with 1 shotgun shot
Pick up shotgun
Find third secret
Find first secret