Red Faction

Note: All weapon-related trophies count across all saves. If you want you can make a save near enemies, kill them, reload the save and repeat the process for every trophy.

The Flamethrower is first acquired just before the Barracks. This can be slightly annoying to get kills with, due to the fact you have to get close to burning enemies. Like most weapons, there are more than enough of these throughout the game.