Here is the full list of all 30 Gleamlight achievements.
Died 100 times.
Saw it all with the child
Defeated the annihilator, and gained a new power.
Summoned a child in a revived world.
Journeyed to the end, and watched the credits.
Defeated the singularity of all.
The dark being opened a road further in.
Defeated the dark being within a new journey.
Defeated the free-flying within a new journey.
Defeated the road block within a new journey.
Defeated the devoted within a new journey.
Save data erased.
Summoned a child in a destroyed world.
Defeated the demolisher of the human world, and watched the credits.
Defeated the demolisher of the human world.
Defeated the ruler of the skies, and gained a new power.
Defeated the destroyer, and gained a new power.
Defeated the approaching giant, and gained a new power.
Defeated the road block, and gained a new power.
Defeated 100 machines.
Defeated the free-flying once again, and gained a new power.
Obtained the dark being's sword, and gained a new power.
Defeated the dark being, and watched the credits.
Defeated a dark being resembling yourself.
Defeated the free-flying, and gained a new power.
Defeated 10 machines.
Defeated 100 ghosts.
Defeated the devoted, and gained a new power.
Defeated 50 ghosts.
Defeated 10 ghosts.