Here is the full list of all 26 Hitman GO: Definitive Edition achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Kill 100 enemies using the Silverballers.
Kill 100 Pair (Grey) enemies.
Complete all objectives in all chapters without using a single hint.
Complete all objectives in the St. Petersburg Stakeout Chapter.
Complete all objectives in the sixth chapter.
Complete all objectives in the opera chapter.
Die at least 200 times.
Complete all objectives in the fourth chapter.
Play for at least 5,000 turns.
Complete all objectives in the third box.
Kill 100 Patrol (Yellow) enemies.
Kill 100 Turning (Teal) enemies.
Crush three enemies under a falling statue.
Get pushed 100 steps.
Get chased by three guard dogs simultaneously.
Kill 100 Static (Blue) enemies.
Complete all objectives in the second box.
Kill 5 enemies at once.
Worn all three disguise types.
Killed an enemy by emerging from a Secret Passage.
Complete all objectives in the first box.
Play for at least 1,000 turns.
Throw an object without alerting anyone.
Killed 2 enemies at once.
Used a hint, ignored the instructions but finished the level...
Play for at least 100 turns in a single level.