Stickman Gun Shooter is a physics puzzle disguised as a shooter: your gun spins, so you fire on the rotation rather than aiming freely, and the yellow stickmen react with full ragdoll physics when hit.
That turns each level into a timing problem — the shot exists only for a moment as the barrel sweeps past, and a body knocked into another can clear two targets at once.
You don't — the gun spins continuously, so you fire on the rotation. Timing the shot as the barrel sweeps past is the whole mechanic.
Yes — a stickman knocked into another can take both out, which is often how the tighter levels are meant to be solved.
Yes — tap to fire. Nothing to install.