I've glory killed every demons and killed with a melee attack lost souls just in case, and it didn't unlock. Below is gonna be the list of the demons i've killed.

- Summoner – Mission 4 onwards
- Baron of Hell – Mission 6 onwards
- Cacodemon – Mission 6 onwards
- Hell Knight – Mission 2 Onwards
- Imp – From the beginning of the game
- Mancubus – Mission 5 onwards
- Pinky – Mission 7 onwards (Note: Should be your last one if you’ve been Glory Killing every enemy you can. You’ll encounter it a third of the way through Mission 7.)
- Revenant – Mission 5 onwards
- Possessed Soldier – Mission 1 onwards
- The Possessed – From the beginning of the game
- Possessed Engineer – Mission 3 onwards (Note: Mars only)
- Unwilling – Mission 5 onwards (Note: These are rare on Mars, but much more common in Hell. They are very weak; only melee them twice in a row, do not use guns.)
- Hell Razer – Mission 3 onwards
- Possessed Security – Mission 3 onwards (Note: Mars only)

I also killed some lost souls with a melee attack. and did all glory kills on all the bosses

- Cyberdemon
- The three guards
- Spider Mastermind

it didn't unlock.. It's the last achievement i'm missing.

It works I just unlock it.