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.
Pop a Wizgog without using the Arbalest.
Build a small tower in the Culling Grounds.
Send a corpse down the shaft in the Tower of Cogs.
Repair the Solar Engine.
Clear the crypt without using the flashlight.
Complete every cog puzzle and unlock Sebastian's safe.
Obtain the Grasp.
Collect all the tapes in the game.
Meet the Beast.
Complete the game within a 93 minute runtime.
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.
Play the Cosmic Key.
Blast 10 corpses with a single Arbalest shot.
Kill the Mother Wizgog.
Dismember 44 limbs.
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.
Read all the stories of the people of Ember.