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