Here is the full list of all 15 Alchemist's Secret achievements.
Complete 5 games in the Very Easy difficulty
Complete 10 games in the Very Easy difficulty
Complete 5 games in the Easy difficulty
Complete 10 games in the Easy difficulty
Complete 20 games in the Easy difficulty
Complete 3 games in the Insane difficulty
Complete 7 games in the Insane difficulty
Complete 10 games in the Insane difficulty
Complete 20 games in the Very Easy difficultu
Complete 4 games in the Hard difficulty
Complete 5 games in the Normal difficulty
Complete 10 games in the Normal difficulty
Complete 20 games in the Normal difficulty
Complete 8 games in the Hard difficulty
Complete 12 games in the Hard difficulty