Here is the full list of all 28 Metal: Hellsinger achievements. It takes around 5-6 hours to unlock all of the achievements on Windows.
Never hit off-beat in a Hell
Killed two Seraphs in one attack
Died 20 times
Died in a Chaos Crystal explosion
Cleared a Hell using only Paz
Destroyed the Red Judge
Completed all Torments
Destroyed the Red Judge aspect in Acheron
Killed 25 enemies while maintaining a Hit Streak
Destroyed the Red Judge aspect in Nihil
Reached Hit Streak: 50
Destroyed the Red Judge aspect in Gehenna
Destroyed the Red Judge aspect in Incaustis
Soared (Dash + jump) 100 times
Obtained all weapons
Destroyed the Red Judge aspect in Yhelm
Killed 50 Behemoths
Got 666 kills (game total)
Destroyed the Red Judge aspect in Stygia
Reached Hit Streak: 35
Killed 8 enemies in 4 seconds
Completed a Torment
Achieved the top result in a Torment
Destroyed the Red Judge aspect in Voke
Killed a Judge's Aspect with Terminus
Reached Hit Streak: 20
Multi-killed 2 enemies
Reached Hit Streak: 10