Here is the full list of all 26 Killer Chambers achievements.
Get your first key
Loot your first coins
Acquire a precious gem for the first time
Complete The Cellars at all difficulties and retire from the worst job ever
Defeat Mascarone smashing him to pieces
Complete The Castle at all difficulties and buy your way into high society
Defeat Archer and repay him in kind
Complete The Garden at all difficulties and abide the laws of nature
Defeat The Siren, even if there's no reason to ever hit a woman
Complete The Forge at all difficulties and break your chains
Defeat the Fire Child because it's past his bedtime
Complete The Palace at all difficulties and learn the magic words
Defeat Lord Grave and get your hands on The Crown
Buy stuff in Fendrel's Shop
Change some gems into gold coins
Own all the hats
Buy at least one of each consumable items
Complete a level without loosing your style
Kneel down 150 times without dying
Jump as a bunny 50 times without dying
Use the power of the Stray Hat 20 times without dying
Use the Stop Watch 50 times
Glide with the Heaven's Mask for at least 2 seconds
Escape from The Curse for the first time
Escape all the variations of The Curse
Earn all achievements