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