Here is the full list of all 31 The Dark Eye: Memoria achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Find the Caverns of Fail.
Persuade the spirit of air to help you straight away.
Give all items to Xerxes.
Stone, dust, stone, dust.
Find the fox within the labyrinth.
Catch the rabbit at the first try.
Tread lightly.
Find out who of the adventuring party lies at the first try.
Does Bryda know who you really are?
Try to tear down the wall with the golem.
Do You Like Riddles?
Make your decision.
Complete Chapter Eight.
Complete Chapter Seven.
Complete Chapter Six.
Complete Chapter Five.
Collect all elementals.
Adjust the horns towards the spheres.
Throw all items into the chasm.
Complete Chapter Four.
Ashes to ashes, stone to dust.
Complete Chapter Three.
Defeat the spider.
The forest is my home.
Complete Chapter Two.
Give Bryda the wrong astral accumulator.
Shards crack loudly.
Do you have the guts to start an argument?
Turn the pig on the grill.
Complete Chapter One.