Originally Posted by ZafierX

achievements like hard stuff to do, not most kills. Like u know how u can beat halo 1 legendary and get a medal? well in all xbox360 games people can see ur medals online and some medals are extremely hard to get and all of this contributes to ur gamerscore. So you can't just play one game, u have to play alot and be good at all types fo games to get ur gamerscore high.