Here is the full list of all 35 Avernum: Escape From the Pit achievements.
Complete all three game-winning quests in Avernum and never set the difficulty below Normal.
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.
Discover a route back to the surface world. There must be one somewhere.
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.
Meet the Archmage Erika.
Join the Scimitar.
Avernum has five dragons. See if you can whittle that down a bit.
Learn 6 mage spells at level 3.
Steal the treasure from Gremlin's Gold.
Reform a legendary blade from Avernum's past.
Find something that lets you fly.
Discover 50 locations of interest.
Have ten potions made.
Enter the Castle at last.
Learn 6 priest spells at level 3.
Dig up 5 caches.
Learn a priest spell at level 3.
Slay 1000 foes.
The mayor of Formello lost something of great value. Recover it.
Learn a mage spell at level 3.
Discover 10 locations of interest.
Slay 100 foes.
Purge a nefarious infiltrator from Silvar's sewers.
Open a secret door.
Escape the tunnels under Fort Avernum.
Learn 18 mage spells at level 3.
Learn 18 priest spells at level 3.
Get a dread curse. Then cure it.
Dig up 40 caches.
Have fifty potions made.
Find the secret at the bottom of Lost Bahssikava.
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.