Here is the full list of all 26 ASSASSINATION BOX achievements.
GET PROFILE LEVEL 100
GET PROFILE LEVEL 75
GET PROFILE LEVEL 50
GET 100,000 ASSASSINATION POINTS
GET RANK "S" FOR THE FIRST TIME
GET "S" RANK ON EVERY LEVEL IN TAKEOVER MODE
FULLY UPGRADE SLOW TIME
GET PROFILE LEVEL 25
FULLY UPGRADE DASH
FULLY UPGRADE MONEY
FULLY UPGRADE DODGE
FULLY UPGRADE JUMP
GET TOTAL 1000 KILLS
FULLY UPGRADE ACTION POINTS
FULLY UPGRADE MOVEMENT
FULLY UPGRADE GRENADES
GET PROFILE LEVEL 10
GET 10,000 ASSASSINATION POINTS
FULLY UPGRADE AMMO
KILL 100 ENEMIES IN ONE GAME
BUY EVERY UPGRADE FOR ONE WEAPON
GET 100 HEADSHOTS
FULLY UPGRADE HEALTH
BUY ANY CUSTOM PART
SO YOU ACTUALLY MANAGED TO RUN THE GAME
GET "S" RANK ON EVERY LEVEL IN SURVIVAL MODE