Curl

a straight swipe flies straight. bend yours.

pull the ball back and let go -- spin bends the flight around the wall

Pull back and release, like a sling: how far sets the pace, how far across sets the spin. Spin pushes the ball the same way every frame, so a longer flight bends further. The dim second ball has no spin, for comparison.

Concepts: spin, trajectory.

An interactive you play with one thumb, on Wundr.