Here is the full list of all 20 Dark Gates achievements.
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Save Game
Scare a monster
Land a maximum damage hit
Land a critical hit
Destory Dark Gates on easy difficulty
Destory Dark Gates on normal difficulty
Destory Dark Gates on hard difficulty
Party is dead
All heroes are dead, game over
Kill the Unnamed
Save a party layout for next time
Reset the game
Kill one hero
It's alive!
We want no trouble
Successfully bribe a monster
Successfully negotiate with a monster
Upgrade a hero
Gather 5000 in gold