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