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