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