I think Call of duty didn't have too much blood, it was going toward realism but realistically CoD5 still had underpowered guns realistically as well as little blood spatter (I never saw any) at most it was violent with machine guns ripping arms off but thats actually realistic. Never really played halo (otehr then halo 1) or gears of war, though halo one in this one room i killed a 5 guys and the teh room was painted with blood which i found odd.