Here is the full list of all 43 Dungeon of Gain achievements.
Kill first enemy
Kill 5 enemies
Kill 10 enemies
Kill 100 enemies
Find first item in the chests
Find 5 items in the chests
Find 10 items in the chests
Find 100 items in the chests
Kill the 10 spiders
Kill the 10 goblins
Kill the 10 skeletons
Kill the 10 shadows
First levelup
Gain the 10th level, playing for the warrior
Gain the 10th level, playing for archer
Gain the 10th level, playing as a mage
Buy first item
Buy 10 items
Buy 100 items
Buy 1000 items
Sell first item
Sell 10 items
Sell 100 items
Sell 1000 items
Start playing as warrior
Start game as archer
Start playing as mage
Go to Level 2 of dungeon
Go to Level 5 of dungeon
Go to Level 10 of dungeon
Activate the altar of life
Activate the altar of mana
Open 100 doors
Finish quest
Finish 5 quests
Finish 10 quests
Kill the necromancer
Get the 3rd level
Get the 5th level
Get 10th level
Get 20th level
Light the torch
Light the one-hundred torches