Here is the full list of all 15 Darkness Assault achievements.
Make 500 shots
Make 200 shots
Kill 25 enemies
Find Beretta 92
Make 50 shots
Find Glock 20
Kill 5 enemies
Kill your first enemy
Make first shot
Find S&W Model 625 MG
Read any document through game menu
Die 25 times
Die 10 times
Die 1 time
Launch game with Ultra Quality