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