Killzone 2

this is not my solution
source:
https://www.playstationtrophies.org/game/killzone-2/trophy/4...

You need to kill each enemy type with a melee attack, either your knife or the blunt end of your gun. Below is a list of all the different units and where they can be found. Here is also a link to a picture showing the different enemy types (be aware though, the Mounted Gunner and Medium Mounted Gunner doesnt need to be carrying a Shotgun, most likely they carry the standard StA52 Assault Rifle). Thanks InfamousHawk for putting together the list



Advanced Shock Trooper - Mission: Tharsis Refinery, Section: Central Observatory
Assault Infantry Advanced - Mission: Visari Palace, Section: Inner Courtyard
Assault Infantry - Mission: Corinth River, Section: Corinth Sands
Commando - Mission: Salamun District, Section: Dushan Tower Courtyard
Elite Shock Trooper - Mission: The Cruiser, Section: Launch Bay
Grenadier - Mission: Visari Palace, Section: Inner Courtyard
LMG Trooper - Mission: Visari Palace, Section: Lazar Highway
Miner - Mission: Suljeva Village, Section: Suljeva North
Mounted Gunner Medium - Mission: Visari Palace, Section: Lazar Highway
Mounted Gunner - Mission: Corinth River, Section: Korovis Dam
Pyro Trooper - Mission: The Cruiser, Section: Launch Bay
Rifleman - Mission: Corinth River, Section: Verdran Overlook West
Shock Trooper - Mission: Tharsis Refinery, Section: Suljeva Minetrain
Scout Sniper - Mission: Suljeva Village, Section: Vojislav Mining Facility
Support Trooper - Mission: Corinth River, Section: Verdran Overlook East