Here is the full list of all 36 Gloom achievements.
A pillar of demented art
One-of-a-kind weapon
He had it coming
No more dreaming, no more nightmares
A pillar of demented faith
A place for ascension
A mirror of null existence
A ghastly tide of salvation
A place for silence and emptiness
A narrator of nightmares
An orphan of spite
A place for expression and madness
An agent of secrecy
A place for the shunned and forgotten
An instrument of ascension
A fallen deity of envy
All for one
A place for the lost and demented
A false prophet of ill omens
An embodiment of deific anger
Resilience is a virtue
You perished in a dream
An embryo of the cosmic way
The book in all its glory
Well that's just sadistic
A grander existence
You've got the hang of it
Must be routine at this point
Win in less than 12 minutes
Win in less than 8 minutes and 30 seconds
Three wins in a row
Ten wins in a row
A place for gloom
Most renowned of them all
Leo's blades and both eyes simultaneously
To retrieve what was once lost