Here is the full list of all 35 Avernum: Escape From the Pit achievements.
Have ten potions made.
Learn 18 mage spells at level 3.
Learn a priest spell at level 3.
Learn 6 priest spells at level 3.
Learn 18 priest spells at level 3.
Get a dread curse. Then cure it.
Have fifty potions made.
Discover 50 locations of interest.
Steal the treasure from Gremlin's Gold.
The mayor of Formello lost something of great value. Recover it.
Enter the Castle at last.
Avernum has five dragons. See if you can whittle that down a bit.
Discover a route back to the surface world. There must be one somewhere.
Complete all three game-winning quests in Avernum and never set the difficulty below Hard.
Complete all three game-winning quests in Avernum and never set the difficulty below Torment.
Find something that lets you fly.
Learn 6 mage spells at level 3.
Slay 100 foes.
Find the secret at the bottom of Lost Bahssikava.
Purge a nefarious infiltrator from Silvar's sewers.
Discover 10 locations of interest.
Join the Scimitar.
Learn a mage spell at level 3.
Slay 1000 foes.
Dig up 5 caches.
Dig up 40 caches.
Sss-Thsss will trouble Avernum no longer.
Purge a certain powerful demon from the Tower of Magi. Phew. Hope they stay out of trouble in the future.
Reform a legendary blade from Avernum's past.
Meet the Archmage Erika.
Destroy the demon Grah-Hoth, making Avernum safe from his menace at last.
Deliver harsh vengeance to the cruel tyrant who sent the Avernites into the underworld.
Complete all three game-winning quests in Avernum and never set the difficulty below Normal.
Open a secret door.
Escape the tunnels under Fort Avernum.