Sniper challenge

Sniping is the use of stealth and marksmanship to achieve surprise. As such it is not limited to any particular weapon, though a scoped rifle is the usual choice. Sly use of concealed cannons, as sometimes occurred in the World Wars, counts as sniping. So does taking out a spy across a street by the use of a sound-suppressed pistol.

All the same, the classic use of sniping as a tactic involves crawling around in the weeds with a precision rifle with an optic on it. Let's brainstorm a bit and see if we can come up with more uses for an expert shot who shows up where the enemy does not expect him. His armament may be any aimed weapon if you can get it there unnoticed.

Challenge: Think of ways to make use of the basic ideas of sniping, but think in terms of unusual weapons, unusual targets or both.