Here is the full list of all 21 Schein achievements.
Completed Schein with less than 100 deaths.
Completed Schein with less than 50 deaths.
Listened to the secret dialog.
All collectibles found.
Kept the blue light lit for 60 seconds.
Caught a lantern mid-air 25 times.
Completed Schein.
Half of all collectibles found.
Left the lantern behind.
Ride platforms for a total of 5000 meters.
Died in fire 100 times.
Defeated Ermatu.
Kept the red light lit for 60 seconds.
Died on spikes 100 times.
Defeated Sartasis.
Died in water 100 times.
First collectible found.
Defeated Zenel.
Kept the green light lit for 60 seconds.
Walked left at the beginning.
Met the Irrlicht.