Here is the full list of all 35 Avernum 2: Crystal Souls achievements.
Complete all three game-winning quests in Avernum 2 and never set the difficulty below Normal.
Slay the commander of the invading army.
Keep the Empire from flooding Avernum with troops.
Win Avernum a powerful ally in its war.
Get a really sweet sword.
Learn 8 priest spells at level 3.
A sharp knife. Find one.
Fully prove your worth to Avernum.
Sanctify 5 altars.
Escape the bonds of gravity.
Learn 8 mage spells at level 3.
Return a Crystal Soul.
Meet the greatest mage in Avernum.
Discover 70 locations of interest.
Find each class of Empire pass.
Slay Elderan.
Dig up 10 caches.
Learn a mage spell at level 3.
Learn a priest spell at level 3.
Return to Avernum from the depths.
Discover 20 locations of interest.
Survive a long river journey.
Meet an envoy from the deepest caves.
Open a secret door.
Escape the caves above Fort Ganrick.
Complete all three game-winning quests in Avernum 2 and never set the difficulty below Hard.
Complete all three game-winning quests in Avernum 2 and never set the difficulty below Torment.
Learn 20 mage spells at level 3.
Learn 20 priest spells at level 3.
Dig up 40 caches.
Have ten potions made.
Have fifty potions made.
Make there be one fewer dragon. (Normal difficulty or higher.)
Avenge the lost Avernites of Cotra.
Fill up a spirit prism.