Here is the full list of all 27 The Gallery - there are Episode 2: Heart of the Emberstone achievements.
Solve every Gauntlet puzzle.
Complete Episode 2.
Repair the Solar Engine.
Clear the crypt without using the flashlight.
Send a corpse down the shaft in the Tower of Cogs.
Complete every cog puzzle and unlock Sebastian's safe.
Dismember 44 limbs.
Obtain the Grasp.
Kill the Mother Wizgog.
Meet the Beast.
Complete the game within a 93 minute runtime.
Collect all the tapes in the game.
Finish the game without harming any Wizgogs.
Kill every Wizgog in the Culling Grounds.
Reunite the spectators of the Cull.
Give Hermie a new home.
Pop a Wizgog without using the Arbalest.
Play the Cosmic Key.
Blast 10 corpses with a single Arbalest shot.
Activate the Easter Egg.
Have a nap in the Transport Room tent.
Kill the captured Wizgog.
Collect, view, and read all the lore in the game.
View all the Polaroids in the game.
Build a large tower in the Culling Grounds.
Build a small tower in the Culling Grounds.
Read all the stories of the people of Ember.