Here is the full list of all 22 Caves and Castles: Underworld achievements worth 1,000 gamerscore.
Spent two hours in the dungeon
Opened 40 chests
Earned 100000 coins
Exchanged the essence for 15000 coins
Completed 30 dungons
Opened 20 chests
Spent over 10 minutes watching the settlement
Summoned the dragon 10 times
Met the lemur
Built 10 houses
Earned 50000 coins
Met the dragon
Destroyed 125 stone blocks
Built 5 houses
Completed 10 dungeons
Opened first chest
Met the chick
Earned 10000 coins
Destroyed 72 stone blocks
Built first house
Destroyed 50 stone blocks
Completed first dungeon