Daruk has just submitted some Achievement Flag Info for
Slay the Spire Achievements:
Daruk said:The Purity achievement in Slay the Spire worth 20 pointsHave 3 or fewer cards in hand, draw, and discard pile combined. This achievement is (or at least was) "buggy". If I'm right, it instantly unlocked (at the 1st second after launch) the 1st time I launched the game.