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