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