Here is the full list of all 35 Avernum: Escape From the Pit achievements.
Purge a certain powerful demon from the Tower of Magi. Phew. Hope they stay out of trouble in the future.
Get a dread curse. Then cure it.
Have ten potions made.
Learn 6 mage spells at level 3.
Find something that lets you fly.
Steal the treasure from Gremlin's Gold.
Join the Scimitar.
Learn 6 priest spells at level 3.
Meet the Archmage Erika.
Avernum has five dragons. See if you can whittle that down a bit.
Sss-Thsss will trouble Avernum no longer.
Find the secret at the bottom of Lost Bahssikava.
Learn a mage spell at level 3.
Discover 50 locations of interest.
Learn a priest spell at level 3.
Enter the Castle at last.
Dig up 5 caches.
Slay 1000 foes.
The mayor of Formello lost something of great value. Recover it.
Purge a nefarious infiltrator from Silvar's sewers.
Discover 10 locations of interest.
Open a secret door.
Slay 100 foes.
Escape the tunnels under Fort Avernum.
Learn 18 mage spells at level 3.
Learn 18 priest spells at level 3.
Dig up 40 caches.
Have fifty potions made.
Reform a legendary blade from Avernum's past.
Destroy the demon Grah-Hoth, making Avernum safe from his menace at last.
Discover a route back to the surface world. There must be one somewhere.
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.
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.