Here is the full list of all 25 Ereban: Shadow Legacy achievements.
You are now part of the creed
Use Shadow Control on a worker
Unlock the Hope Ending
Obtain a 'S' rank in every chapter
Obtain the Merciful medal in every chapter
Unlock the Light Ending
Craft and improve every gadget
Learn all the non-lethal and mixed shadow powers
Scan the crow in Chapter III with the visor
Use Shadow Vortex on three or more enemies in a row before materializing
Learn all the lethal and mixed shadow powers
Obtain the Ruthless medal in every chapter
Obtain the Ghost medal in every chapter
Unlock the Darkness Ending
Use Shadow Merge to avoid a HAWK shot
Paralyze three or more SYMs with a single mine
Complete Chapter VI
Open the secret room in Chapter VI
Complete Chapter V
Help Helena to find out what happened to her family in Chapter V
Get detected by three or more SYMs at the same time
Help Gerel escape with his cell in Chapter IV
Help Kelsa and all her team in Chapter III
Complete Chapter II
Complete Chapter I