Here is the full list of all 35 Avernum: Escape From the Pit achievements.
Dig up 40 caches.
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.
Have fifty potions made.
Learn 18 priest spells at level 3.
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.
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.
Join the Scimitar.
Have ten potions made.
Sss-Thsss will trouble Avernum no longer.
Find something that lets you fly.
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.
Get a dread curse. Then cure it.
Find the secret at the bottom of Lost Bahssikava.
Learn 6 mage spells at level 3.
Meet the Archmage Erika.
Avernum has five dragons. See if you can whittle that down a bit.
Discover 50 locations of interest.
Learn 6 priest spells at level 3.
Learn a priest spell at level 3.
Learn a mage spell at level 3.
Slay 1000 foes.
Steal the treasure from Gremlin's Gold.
Dig up 5 caches.
Enter the Castle at last.
The mayor of Formello lost something of great value. Recover it.
Discover 10 locations of interest.
Slay 100 foes.
Open a secret door.
Purge a nefarious infiltrator from Silvar's sewers.
Escape the tunnels under Fort Avernum.