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.
Does Bryda know who you really are?
Stone, dust, stone, dust.
Find the Caverns of Fail.
Persuade the spirit of air to help you straight away.
Tread lightly.
Find out who of the adventuring party lies at the first try.
Do You Like Riddles?
Throw all items into the chasm.
Make your decision.
Complete Chapter Eight.
Complete Chapter Seven.
Complete Chapter Six.
Complete Chapter Five.
Collect all elementals.
Adjust the horns towards the spheres.
Give all items to Xerxes.
Complete Chapter Four.
Ashes to ashes, stone to dust.
Complete Chapter Three.
Defeat the spider.
The forest is my home.
Find the fox within the labyrinth.
Complete Chapter Two.
Catch the rabbit at the first try.
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.
Try to tear down the wall with the golem.