Here is the full list of all 23 Hero's Descent achievements.
Defeat the Slime King
Defeat the 3 Necromancers before the Dark Knight
Defeat the Dark Knight
Defeat the Dark Wizard
Reach the deepest floor of the castle and reveal the truth!
Complete the game in under 8 minutes
Complete the game in under 5 minutes
Complete the game in under 3 minutes. You're a Hero's Descent pro!
Defeat the Fairy Queen. Something is odd about the castle now, though...
Discover something beyond understanding
You made it out alive...this time
Complete the game as the Hero!
Complete the game as the Wizard
Complete the game as the Berserker!
You killed at least 100 rats. Are you satisfied now, you monster?
You killed at least 20 bats. Honestly, they've probably killed you far more times than that by now.
You knew the risks, but you took up the axes anyways.
You got lucky this time, maybe don't try that again...
It wouldn't be an RPG without one of these.
You killed at least 30 mimics. You're starting to look forward to the Storm of Greed now, aren't you?
On the fourteenth morning's chill, from the rampart he is spotted on the hill.
You burned at least 3 enemies with the same cast of Firestorm. Maybe cool down a bit?
You...you managed to score over 800 points in a single run?