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