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
Died 20 times
Died in a Chaos Crystal explosion
Cleared a Hell using only Paz
Killed two Seraphs in one attack
Destroyed the Red Judge
Soared (Dash + jump) 100 times
Completed all Torments
Destroyed the Red Judge aspect in Acheron
Destroyed the Red Judge aspect in Nihil
Destroyed the Red Judge aspect in Gehenna
Killed a Judge's Aspect with Terminus
Killed 25 enemies while maintaining a Hit Streak
Reached Hit Streak: 50
Killed 8 enemies in 4 seconds
Killed 50 Behemoths
Completed a Torment
Achieved the top result in a Torment
Destroyed the Red Judge aspect in Incaustis
Got 666 kills (game total)
Obtained all weapons
Destroyed the Red Judge aspect in Yhelm
Destroyed the Red Judge aspect in Stygia
Destroyed the Red Judge aspect in Voke
Reached Hit Streak: 35
Reached Hit Streak: 20
Multi-killed 2 enemies
Reached Hit Streak: 10