Sniper: Ghost Warrior

This is probably the longest trophy in the whole game. Kill a total of 2000 enemies in the online mode to unlock this shiny gold trophy. You will probably have unlocked every other online trophy by the time you have your 2000 kills together.

BOOST METHOD:

To boost kills properly, you will need a group of 4 people working together. Have the host set up a CTF match in Ruins, 20 minutes long. The other 3 then find him using custom match. If you want to keep the teams the same every match, note that the last of the 3 to join will end up on the hosts team.

The idea is to exploit spawn kills, where each man gets 10 minutes of killing time. At the start, one player from each team goes to the enemy base, the other stays behind. Look at the rough map below:

There is a small pile of blue crates in each base. The shooter stands on it. The victim stands in the corner shown by the spot on the map. The shooter can then kill at will. The victim will keep spawning in the same spot. At the ten minute mark, each team switches shooter and victim. This way all four players get around 70 kills per match.

To pick up a win, simply bring back the flag during the halfway switch. This should be shared, alternating each match.