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