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.
Find out about the last story of Venigni.
Decipher all cryptic vessels and claim the rewards.
Find out about the last story of Eugénie.
Collect all special weapons.
Learn all gestures.
Collect all Legion Arms.
Collect all normal weapons.
Discover all Trinity Sanctums.
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 Sophia.
[Rise of P] Reach the ending.
Play a perfect tune on the piano at Hotel Krat.
[Free from the puppet string] Reach the ending.
Kill the Nameless Puppet.
Activate P-Organ to Phase 5.
Strengthen a special weapon to its max level.
Find out about the last story of Simon Manus.
Kill the Awakened God Simon Manus.
Strengthen a normal weapon to its max level.
Find out about the last story of Antonia.
Kill Laxasia the Complete.
Kill the Corrupted Parade Master.
Kill the Black Rabbit Brotherhood.
Kill the Puppet-Devouring Green Monster.
Modify a Legion Arm to its max level.
Kill Champion Victor.
Kill all types of Dimensional Butterflies.
Kill Romeo, King of Puppets.
Harvest Gold Coin Fruit.
Kill the Eldest of the Black Rabbit Brotherhood.
Kill the Fallen Archbishop Andreus.
Try to assemble a weapon.
Kill King’s Flame, Fuoco.
Kill the Scrapped Watchman.
Kill a Stalker.
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.