6. The AWP Rifle - Counter-Strike
If you've played Counter-Strike, you'll instantly realise that the choice of gun for players is almost exclusively the AWP rifle. It's overused, overpowered, and overly-hated in a community that continues to cry for it to be nerfed.
The gun is infamous for its ability to score the wielder a guaranteed one-hit kill anywhere on the body except the legs, regardless of whether the player has armour or not.
The rifle has a scope, but you don't even need to use it as the gun is a one-shot at any range and a completely viable tactic is to blast at a foe without aiming for an easy kill. It's not just in the original game either, as in Counter-Strike: Global Offensive the weapon has found a new home to be just as annoying.
The only saving grace to numb the effects of its obscene stopping power is its long-reload time and weight. However, in the experienced hands of the deep Counter-Strike community the pros far outweigh the cons, and it will forever be debated whether or not this behemoth of online play is merely very useful or simply flat-out broken.