Here is the full list of all 35 Avernum: Escape From the Pit achievements.
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 Normal.
Complete all three game-winning quests in Avernum and never set the difficulty below Hard.
Have fifty potions made.
Dig up 40 caches.
Destroy the demon Grah-Hoth, making Avernum safe from his menace at last.
Learn 18 priest spells at level 3.
Deliver harsh vengeance to the cruel tyrant who sent the Avernites into the underworld.
Learn 18 mage spells at level 3.
Join the Scimitar.
Avernum has five dragons. See if you can whittle that down a bit.
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.
Learn 6 mage spells at level 3.
Meet the Archmage Erika.
Steal the treasure from Gremlin's Gold.
Have ten potions made.
Find something that lets you fly.
Sss-Thsss will trouble Avernum no longer.
Get a dread curse. Then cure it.
Discover 50 locations of interest.
Learn 6 priest spells at level 3.
Find the secret at the bottom of Lost Bahssikava.
Slay 1000 foes.
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.
Learn a mage spell at level 3.
Learn a priest spell at level 3.
Open a secret door.
Slay 100 foes.
Purge a nefarious infiltrator from Silvar's sewers.
Escape the tunnels under Fort Avernum.
Complete all three game-winning quests in Avernum and never set the difficulty below Torment.