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