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