At my first playthrough I managed to get about 1,000 kills. That's pretty much 1% :P

It won't really be THAT hard with how addicting Horde mode is and everything, I always see my achievement counter pop up in the corner randomly and I don't even pay attention.

Some people had more than 100k kills in Gears 1 in multiplayer ALONE, so yeah.

Lol and I thought 10k kills in competitive multiplayer in Resistance 2 was a lot....
Good luck with that guys...
I still think Warhawk General is the most time consuming trophy ever...( Average 1000 hours or so, I think less than 50 players have it worldwide more than 1 year after the release of the game..)

I'm aiming for it, I have got over 1k kills and I am half way through act 5, I know there is there is somewhere in the campaign where you can get an insane number of kills in a short time, so I am just going to replay that. I might also be joining in in some horde. I doubt that much of it will come from online games, because I think I'll be dying quite a lot in that

Considering I put a total of like 12 days (12 x 24 hours) in CoD4 and STILL did not have 100,000 kills.... I don't think I'll be getting this achievement. Especially since CoD4 was a lot easier to kill people and I had matches with like 20+ kills on a regular basis.