Here is the full list of all 42 Lies of P achievements. It takes around 60-80 hours to unlock all of the achievements on Windows.
Collect and play all records.
Collect all special weapons.
Find out about the last story of Antonia.
Learn all gestures.
[Free from the puppet string] Reach the ending.
Find out about the last story of Eugénie.
Kill a Stalker.
Find out about the last story of Sophia.
[Rise of P] Reach the ending.
Kill the Nameless Puppet.
Play a perfect tune on the piano at Hotel Krat.
Find out about the last story of Geppetto.
[Real boy: They all lived happily ever after] Reach the ending.
Find out about the last story of Simon Manus.
Kill the Awakened God Simon Manus.
Decipher all cryptic vessels and claim the rewards.
Collect all normal weapons.
Kill Laxasia the Complete.
Find out about the last story of Venigni.
Discover all Trinity Sanctums.
Strengthen a normal weapon to its max level.
Strengthen a special weapon to its max level.
Kill the Black Rabbit Brotherhood.
Activate P-Organ to Phase 5.
Collect all Legion Arms.
Kill the Corrupted Parade Master.
Modify a Legion Arm to its max level.
Kill the Puppet-Devouring Green Monster.
Kill Champion Victor.
Kill all types of Dimensional Butterflies.
Kill Romeo, King of Puppets.
Kill the Eldest of the Black Rabbit Brotherhood.
Harvest Gold Coin Fruit.
Kill the Fallen Archbishop Andreus.
Try to assemble a weapon.
Kill King’s Flame, Fuoco.
Kill the Scrapped Watchman.
Tell a lie in front of Hotel Krat Entrance.
Kill the Parade Master.
Repair a Stargazer.
Destroy an enemy’s weapon with a perfect guard.
Deliver a successful Fatal Attack.