Here is the full list of all 29 Sydney Hunter and the Curse of the Mayan achievements.
Defeated Kukulkan in serpent form
Fully upgraded your whip
Acquired the sun block from Anna
Collected Gems 867-5309
Acquired the mask relic
Defeated the Maize Deity
Purchase first Maya Meal
Defeated the Bee Deity
Collected the Boomerang
Collected the Spear
Defeated the Jaguar Deity
Killed first ghost
Kill 1st snake
Statue Save Game Checkpoint used for first time
Killed 25 bats in any level
Everyone gets a participation trophy
Defeated the Rain Deity
Defeated all gods during the boss rush
Defeated the Sun Deity
Defeated the Death Deity
Defeated Kukulkan human form
Collected all Yellow Diamonds
Collected Kukulkan's key
Defeated the Lava Idol
Completed the game with good ending.
Yuki gets her lost HuCard
Found all treasures in Shrines of Peril Arcade Game
Found all Crystal Skulls
Sydney on Ice. Bad Ending