Perfect Dark Zero

The little trick in my video should help you get 1000 kills in no time at all. You should have a second controller for this. It isn't required, but is highly advised.

Match setup:
Team Killcount (Deathmatch)
Map: Desert, small variant
Custom weapon setup:
In slot 1 - 4 add shield
In slot 5 add the Plasma Rifle
Bot setup:
Bot count: 14 (to allow your other player to join)
Difficulty: Agent
Bot teams: Humans vs Bots
Personality: Bully

Set the time / score limit to whatever suits you, just make sure you don't set the time limit to infinite (the game won't be able to end properly and the kills won't count toward the achievement.) 20 minutes with no score limit will net you over 500 kills.

start a local team deathmatch game with easy bots make it bots vs humans and a 50 kill limit and do your best to kill as many possible game over = rince and repeat untill cheevo
note cheevo unlocks upon games end

I realize this game is a bit old and there probably wont be many people seeing a new guide for this, but for the sake of future people going for that coveted Stampers Forever Achievement, I have a new strategy. This will net you the 1000 explosive kills as well as the Team Killcount kill achievements. First things first, open up a round of team kill count on Old Town with small variant and as many bots as possible (15) active. Put those bots on agent difficulty and set the match to bots vs humans. This will increase the number of kills you get in a short period of time. Now, turn off friendly fire so you can't kill yourself and create a custom class with entirely mines. The time and score limit is up to you but I recommend you go unlimited time and 100 kills. Once the match starts find a nice corner somewhere that the only attack point the bots have is right in front of you. You'll want to start tossing mines right in front of you. The mines will create a blast cloud that will kill any bots that run into it, as well as exploding future mines you throw. Just keep throwing mines into the blast cloud and the stupid bots will keep trying to kill you, but die in the process. Because all weapons are mines as well, their deaths will give you more ammo. Rinse and repeat until you have all 1000 kills. I feel I should note that sometimes they can get a hit off by rolling into the cloud, but even if they manage to kill you, you can start right up again. The agent bots are too stupid to properly work mines so they can only really kill you be melee. Anyway, best luck to all who attempt this in the future and I hope this helps. It's a HUGE time saver.