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 Pair (Grey) enemies.
Kill 100 enemies using the Silverballers.
Die at least 200 times.
Used a hint, ignored the instructions but finished the level...
Complete all objectives in the opera chapter.
Complete all objectives in all chapters without using a single hint.
Complete all objectives in the sixth chapter.
Complete all objectives in the fourth chapter.
Complete all objectives in the third box.
Crush three enemies under a falling statue.
Get chased by three guard dogs simultaneously.
Kill 100 Turning (Teal) enemies.
Kill 100 Patrol (Yellow) enemies.
Complete all objectives in the second box.
Complete all objectives in the St. Petersburg Stakeout Chapter.
Get pushed 100 steps.
Play for at least 5,000 turns.
Play for at least 100 turns in a single level.
Complete all objectives in the first box.
Kill 100 Static (Blue) enemies.
Worn all three disguise types.
Play for at least 1,000 turns.
Killed an enemy by emerging from a Secret Passage.
Kill 5 enemies at once.
Killed 2 enemies at once.
Throw an object without alerting anyone.