8. The Farsight Rifle - Perfect Dark
The farsight rifle allowed you to see enemies through walls when they couldn't, and your bullets penetrated through said walls to hit them. Enough said.
It also has a generous lock-on that meant the unsuspecting victim of this weapon would end up running for cover in vain as they are hit from across the map by an invisible force.
As a person wielding such power, it's incredibly satisfying to pick off each poor foe while you don't even need to move. When you're on the receiving end of such torment, however, it's maddening. There next to no defence beyond hoping you manage to gain a good spawn point to quickly flank the player holding it before they see you.
You can expect most of your friends your playing with to label you a hacker before the truth is revealed, and then you all made an agreement that you weren't to pick up this insanely overpowered gun.
Using the farsight rifle is basically playing the game with cheats on.