Here is the full list of all 19 The Hong Kong Massacre achievements.
All challenges completed
10 000 enemies killed
Complete the first and second day without dying
One hour in slowmotion
Died 250 times
Complete first day without dying
All weapons and upgrades unlocked
1000 enemies killed
Game completed
Picked up 50 weapons
Second day completed
25 Doors destroyed
First boss completed
100 enemies killed
Completed a level without slowmotion
Completed a level on first try
First weapon unlocked
First level completed
First enemy killed