Here is the full list of all 12 Hexic HD achievements worth 200 gamerscore. It takes around 20-25 hours to unlock all of the achievements on Xbox 360.
Get a total of 25 combos across all of your games.
Form a cluster of three bonus-star pieces.
Surround one piece with six same-color pieces.
Surround one piece with six starflower pieces.
Form a cluster of three black pearls.
Complete 100 games of Hexic.
Get a total of 5,000 combos across all of your games.
Complete Survival mode by clearing all of the pieces on one screen or by passing Level 50.
Earn 75,000 points in a single Timed game.
Earn 150,000 points in a single Marathon game.
Earn a total lifetime score of one-million points across all of your games.
Surround one piece with six black pearls.