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