Doesn't Play Well with Others

 is an Fallout 3 achievement on Xbox 360 and PC and a trophy on PlayStation 3.

It is granted for killing 300 people. You can check your progress with your Pip-Boy under Stats, then General. One good idea is to leave it till you have killed 270 people then go and wipe out megaton,(if you didnt blow it away) rivet city, and big town and then recieve the achievment and load your save from before.

But if you do end up going to Rivet City watch out for Harkness. He doesnt EVER die.